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