bfd/binary.c

   1 /* BFD back-end for binary objects.
   2    Copyright 1994, 1995, 1996, 1997, 1998, 1999, 2000, 2001, 2002, 2003,
   3    2004, 2005, 2006, 2007, 2009 Free Software Foundation, Inc.
   4    Written by Ian Lance Taylor, Cygnus Support, <ian@cygnus.com>
   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 /* This is a BFD backend which may be used to write binary objects.
  24    It may only be used for output, not input.  The intention is that
  25    this may be used as an output format for objcopy in order to
  26    generate raw binary data.
  27
  28    This is very simple.  The only complication is that the real data
  29    will start at some address X, and in some cases we will not want to
  30    include X zeroes just to get to that point.  Since the start
  31    address is not meaningful for this object file format, we use it
  32    instead to indicate the number of zeroes to skip at the start of
  33    the file.  objcopy cooperates by specially setting the start
  34    address to zero by default.  */
  35
  36 #include "sysdep.h"
  37 #include "bfd.h"
  38 #include "safe-ctype.h"
  39 #include "libbfd.h"
  40
  41 /* Any bfd we create by reading a binary file has three symbols:
  42    a start symbol, an end symbol, and an absolute length symbol.  */
  43 #define BIN_SYMS 3
  44
  45 /* Set by external programs - specifies the BFD architecture and
  46    machine number to be uses when creating binary BFDs.  */
  47 enum bfd_architecture  bfd_external_binary_architecture = bfd_arch_unknown;
  48 unsigned long          bfd_external_machine = 0;
  49
  50 /* Create a binary object.  Invoked via bfd_set_format.  */
  51
  52 static bfd_boolean
  53 binary_mkobject (bfd *abfd ATTRIBUTE_UNUSED)
  54 {
  55   return TRUE;
  56 }
  57
  58 /* Any file may be considered to be a binary file, provided the target
  59    was not defaulted.  That is, it must be explicitly specified as
  60    being binary.  */
  61
  62 static const bfd_target *
  63 binary_object_p (bfd *abfd)
  64 {
  65   struct stat statbuf;
  66   asection *sec;
  67   flagword flags;
  68
  69   if (abfd->target_defaulted)
  70     {
  71       bfd_set_error (bfd_error_wrong_format);
  72       return NULL;
  73     }
  74
  75   abfd->symcount = BIN_SYMS;
  76
  77   /* Find the file size.  */
  78   if (bfd_stat (abfd, &statbuf) < 0)
  79     {
  80       bfd_set_error (bfd_error_system_call);
  81       return NULL;
  82     }
  83
  84   /* One data section.  */
  85   flags = SEC_ALLOC | SEC_LOAD | SEC_DATA | SEC_HAS_CONTENTS;
  86   sec = bfd_make_section_with_flags (abfd, ".data", flags);
  87   if (sec == NULL)
  88     return NULL;
  89   sec->vma = 0;
  90   sec->size = statbuf.st_size;
  91   sec->filepos = 0;
  92
  93   abfd->tdata.any = (void *) sec;
  94
  95   if (bfd_get_arch_info (abfd) != NULL)
  96     {
  97       if ((bfd_get_arch_info (abfd)->arch == bfd_arch_unknown)
  98           && (bfd_external_binary_architecture != bfd_arch_unknown))
  99         bfd_set_arch_info (abfd, bfd_lookup_arch
 100                            (bfd_external_binary_architecture, bfd_external_machine));
 101     }
 102
 103   return abfd->xvec;
 104 }
 105
 106 #define binary_close_and_cleanup     _bfd_generic_close_and_cleanup
 107 #define binary_bfd_free_cached_info  _bfd_generic_bfd_free_cached_info
 108 #define binary_new_section_hook      _bfd_generic_new_section_hook
 109
 110 /* Get contents of the only section.  */
 111
 112 static bfd_boolean
 113 binary_get_section_contents (bfd *abfd,
 114                              asection *section ATTRIBUTE_UNUSED,
 115                              void * location,
 116                              file_ptr offset,
 117                              bfd_size_type count)
 118 {
 119   if (bfd_seek (abfd, offset, SEEK_SET) != 0
 120       || bfd_bread (location, count, abfd) != count)
 121     return FALSE;
 122   return TRUE;
 123 }
 124
 125 /* Return the amount of memory needed to read the symbol table.  */
 126
 127 static long
 128 binary_get_symtab_upper_bound (bfd *abfd ATTRIBUTE_UNUSED)
 129 {
 130   return (BIN_SYMS + 1) * sizeof (asymbol *);
 131 }
 132
 133 /* Create a symbol name based on the bfd's filename.  */
 134
 135 static char *
 136 mangle_name (bfd *abfd, char *suffix)
 137 {
 138   bfd_size_type size;
 139   char *buf;
 140   char *p;
 141
 142   size = (strlen (bfd_get_filename (abfd))
 143           + strlen (suffix)
 144           + sizeof "_binary__");
 145
 146   buf = (char *) bfd_alloc (abfd, size);
 147   if (buf == NULL)
 148     return "";
 149
 150   sprintf (buf, "_binary_%s_%s", bfd_get_filename (abfd), suffix);
 151
 152   /* Change any non-alphanumeric characters to underscores.  */
 153   for (p = buf; *p; p++)
 154     if (! ISALNUM (*p))
 155       *p = '_';
 156
 157   return buf;
 158 }
 159
 160 /* Return the symbol table.  */
 161
 162 static long
 163 binary_canonicalize_symtab (bfd *abfd, asymbol **alocation)
 164 {
 165   asection *sec = (asection *) abfd->tdata.any;
 166   asymbol *syms;
 167   unsigned int i;
 168   bfd_size_type amt = BIN_SYMS * sizeof (asymbol);
 169
 170   syms = (asymbol *) bfd_alloc (abfd, amt);
 171   if (syms == NULL)
 172     return -1;
 173
 174   /* Start symbol.  */
 175   syms[0].the_bfd = abfd;
 176   syms[0].name = mangle_name (abfd, "start");
 177   syms[0].value = 0;
 178   syms[0].flags = BSF_GLOBAL;
 179   syms[0].section = sec;
 180   syms[0].udata.p = NULL;
 181
 182   /* End symbol.  */
 183   syms[1].the_bfd = abfd;
 184   syms[1].name = mangle_name (abfd, "end");
 185   syms[1].value = sec->size;
 186   syms[1].flags = BSF_GLOBAL;
 187   syms[1].section = sec;
 188   syms[1].udata.p = NULL;
 189
 190   /* Size symbol.  */
 191   syms[2].the_bfd = abfd;
 192   syms[2].name = mangle_name (abfd, "size");
 193   syms[2].value = sec->size;
 194   syms[2].flags = BSF_GLOBAL;
 195   syms[2].section = bfd_abs_section_ptr;
 196   syms[2].udata.p = NULL;
 197
 198   for (i = 0; i < BIN_SYMS; i++)
 199     *alocation++ = syms++;
 200   *alocation = NULL;
 201
 202   return BIN_SYMS;
 203 }
 204
 205 #define binary_make_empty_symbol  _bfd_generic_make_empty_symbol
 206 #define binary_print_symbol       _bfd_nosymbols_print_symbol
 207
 208 /* Get information about a symbol.  */
 209
 210 static void
 211 binary_get_symbol_info (bfd *ignore_abfd ATTRIBUTE_UNUSED,
 212                         asymbol *symbol,
 213                         symbol_info *ret)
 214 {
 215   bfd_symbol_info (symbol, ret);
 216 }
 217
 218 #define binary_bfd_is_local_label_name      bfd_generic_is_local_label_name
 219 #define binary_get_lineno                  _bfd_nosymbols_get_lineno
 220 #define binary_find_nearest_line           _bfd_nosymbols_find_nearest_line
 221 #define binary_find_inliner_info           _bfd_nosymbols_find_inliner_info
 222 #define binary_bfd_make_debug_symbol       _bfd_nosymbols_bfd_make_debug_symbol
 223 #define binary_read_minisymbols            _bfd_generic_read_minisymbols
 224 #define binary_minisymbol_to_symbol        _bfd_generic_minisymbol_to_symbol
 225 #define binary_bfd_is_target_special_symbol ((bfd_boolean (*) (bfd *, asymbol *)) bfd_false)
 226
 227 /* Set the architecture of a binary file.  */
 228 #define binary_set_arch_mach _bfd_generic_set_arch_mach
 229
 230 /* Write section contents of a binary file.  */
 231
 232 static bfd_boolean
 233 binary_set_section_contents (bfd *abfd,
 234                              asection *sec,
 235                              const void * data,
 236                              file_ptr offset,
 237                              bfd_size_type size)
 238 {
 239   if (size == 0)
 240     return TRUE;
 241
 242   if (! abfd->output_has_begun)
 243     {
 244       bfd_boolean found_low;
 245       bfd_vma low;
 246       asection *s;
 247
 248       /* The lowest section LMA sets the virtual address of the start
 249          of the file.  We use this to set the file position of all the
 250          sections.  */
 251       found_low = FALSE;
 252       low = 0;
 253       for (s = abfd->sections; s != NULL; s = s->next)
 254         if (((s->flags
 255               & (SEC_HAS_CONTENTS | SEC_LOAD | SEC_ALLOC | SEC_NEVER_LOAD))
 256              == (SEC_HAS_CONTENTS | SEC_LOAD | SEC_ALLOC))
 257             && (s->size > 0)
 258             && (! found_low || s->lma < low))
 259           {
 260             low = s->lma;
 261             found_low = TRUE;
 262           }
 263
 264       for (s = abfd->sections; s != NULL; s = s->next)
 265         {
 266           s->filepos = s->lma - low;
 267
 268           /* Skip following warning check for sections that will not
 269              occupy file space.  */
 270           if ((s->flags
 271                & (SEC_HAS_CONTENTS | SEC_ALLOC | SEC_NEVER_LOAD))
 272               != (SEC_HAS_CONTENTS | SEC_ALLOC)
 273               || (s->size == 0))
 274             continue;
 275
 276           /* If attempting to generate a binary file from a bfd with
 277              LMA's all over the place, huge (sparse?) binary files may
 278              result.  This condition attempts to detect this situation
 279              and print a warning.  Better heuristics would be nice to
 280              have.  */
 281
 282           if (s->filepos < 0)
 283             (*_bfd_error_handler)
 284               (_("Warning: Writing section `%s' to huge (ie negative) file offset 0x%lx."),
 285                bfd_get_section_name (abfd, s),
 286                (unsigned long) s->filepos);
 287         }
 288
 289       abfd->output_has_begun = TRUE;
 290     }
 291
 292   /* We don't want to output anything for a section that is neither
 293      loaded nor allocated.  The contents of such a section are not
 294      meaningful in the binary format.  */
 295   if ((sec->flags & (SEC_LOAD | SEC_ALLOC)) == 0)
 296     return TRUE;
 297   if ((sec->flags & SEC_NEVER_LOAD) != 0)
 298     return TRUE;
 299
 300   return _bfd_generic_set_section_contents (abfd, sec, data, offset, size);
 301 }
 302
 303 /* No space is required for header information.  */
 304
 305 static int
 306 binary_sizeof_headers (bfd *abfd ATTRIBUTE_UNUSED,
 307                        struct bfd_link_info *info ATTRIBUTE_UNUSED)
 308 {
 309   return 0;
 310 }
 311
 312 #define binary_bfd_get_relocated_section_contents  bfd_generic_get_relocated_section_contents
 313 #define binary_bfd_relax_section                   bfd_generic_relax_section
 314 #define binary_bfd_gc_sections                     bfd_generic_gc_sections
 315 #define binary_bfd_merge_sections                  bfd_generic_merge_sections
 316 #define binary_bfd_is_group_section                bfd_generic_is_group_section
 317 #define binary_bfd_discard_group                   bfd_generic_discard_group
 318 #define binary_section_already_linked             _bfd_generic_section_already_linked
 319 #define binary_bfd_define_common_symbol            bfd_generic_define_common_symbol
 320 #define binary_bfd_link_hash_table_create         _bfd_generic_link_hash_table_create
 321 #define binary_bfd_link_hash_table_free           _bfd_generic_link_hash_table_free
 322 #define binary_bfd_link_just_syms                 _bfd_generic_link_just_syms
 323 #define binary_bfd_link_add_symbols               _bfd_generic_link_add_symbols
 324 #define binary_bfd_final_link                     _bfd_generic_final_link
 325 #define binary_bfd_link_split_section             _bfd_generic_link_split_section
 326 #define binary_get_section_contents_in_window     _bfd_generic_get_section_contents_in_window
 327
 328 const bfd_target binary_vec =
 329 {
 330   "binary",                     /* name */
 331   bfd_target_unknown_flavour,   /* flavour */
 332   BFD_ENDIAN_UNKNOWN,           /* byteorder */
 333   BFD_ENDIAN_UNKNOWN,           /* header_byteorder */
 334   EXEC_P,                       /* object_flags */
 335   (SEC_ALLOC | SEC_LOAD | SEC_READONLY | SEC_CODE | SEC_DATA
 336    | SEC_ROM | SEC_HAS_CONTENTS), /* section_flags */
 337   0,                            /* symbol_leading_char */
 338   ' ',                          /* ar_pad_char */
 339   16,                           /* ar_max_namelen */
 340   bfd_getb64, bfd_getb_signed_64, bfd_putb64,
 341   bfd_getb32, bfd_getb_signed_32, bfd_putb32,
 342   bfd_getb16, bfd_getb_signed_16, bfd_putb16,   /* data */
 343   bfd_getb64, bfd_getb_signed_64, bfd_putb64,
 344   bfd_getb32, bfd_getb_signed_32, bfd_putb32,
 345   bfd_getb16, bfd_getb_signed_16, bfd_putb16,   /* hdrs */
 346   {                             /* bfd_check_format */
 347     _bfd_dummy_target,
 348     binary_object_p,
 349     _bfd_dummy_target,
 350     _bfd_dummy_target,
 351   },
 352   {                             /* bfd_set_format */
 353     bfd_false,
 354     binary_mkobject,
 355     bfd_false,
 356     bfd_false,
 357   },
 358   {                             /* bfd_write_contents */
 359     bfd_false,
 360     bfd_true,
 361     bfd_false,
 362     bfd_false,
 363   },
 364
 365   BFD_JUMP_TABLE_GENERIC (binary),
 366   BFD_JUMP_TABLE_COPY (_bfd_generic),
 367   BFD_JUMP_TABLE_CORE (_bfd_nocore),
 368   BFD_JUMP_TABLE_ARCHIVE (_bfd_noarchive),
 369   BFD_JUMP_TABLE_SYMBOLS (binary),
 370   BFD_JUMP_TABLE_RELOCS (_bfd_norelocs),
 371   BFD_JUMP_TABLE_WRITE (binary),
 372   BFD_JUMP_TABLE_LINK (binary),
 373   BFD_JUMP_TABLE_DYNAMIC (_bfd_nodynamic),
 374
 375   NULL,
 376
 377   NULL
 378 };