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 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_reloc_type_lookup       _bfd_norelocs_bfd_reloc_type_lookup
 225 #define binary_get_reloc_upper_bound        ((long (*) (bfd *, asection *)) bfd_0l)
 226 #define binary_canonicalize_reloc           ((long (*) (bfd *, asection *, arelent **, asymbol **)) bfd_0l)
 227 #define binary_bfd_is_target_special_symbol ((bfd_boolean (*) (bfd *, asymbol *)) bfd_false)
 228
 229 /* Set the architecture of a binary file.  */
 230 #define binary_set_arch_mach _bfd_generic_set_arch_mach
 231
 232 /* Write section contents of a binary file.  */
 233
 234 static bfd_boolean
 235 binary_set_section_contents (bfd *abfd,
 236                              asection *sec,
 237                              const void * data,
 238                              file_ptr offset,
 239                              bfd_size_type size)
 240 {
 241   if (size == 0)
 242     return TRUE;
 243
 244   if (! abfd->output_has_begun)
 245     {
 246       bfd_boolean found_low;
 247       bfd_vma low;
 248       asection *s;
 249
 250       /* The lowest section LMA sets the virtual address of the start
 251          of the file.  We use this to set the file position of all the
 252          sections.  */
 253       found_low = FALSE;
 254       low = 0;
 255       for (s = abfd->sections; s != NULL; s = s->next)
 256         if (((s->flags
 257               & (SEC_HAS_CONTENTS | SEC_LOAD | SEC_ALLOC | SEC_NEVER_LOAD))
 258              == (SEC_HAS_CONTENTS | SEC_LOAD | SEC_ALLOC))
 259             && (s->size > 0)
 260             && (! found_low || s->lma < low))
 261           {
 262             low = s->lma;
 263             found_low = TRUE;
 264           }
 265
 266       for (s = abfd->sections; s != NULL; s = s->next)
 267         {
 268           s->filepos = s->lma - low;
 269
 270           /* Skip following warning check for sections that will not
 271              occupy file space.  */
 272           if ((s->flags
 273                & (SEC_HAS_CONTENTS | SEC_ALLOC | SEC_NEVER_LOAD))
 274               != (SEC_HAS_CONTENTS | SEC_ALLOC)
 275               || (s->size == 0))
 276             continue;
 277
 278           /* If attempting to generate a binary file from a bfd with
 279              LMA's all over the place, huge (sparse?) binary files may
 280              result.  This condition attempts to detect this situation
 281              and print a warning.  Better heuristics would be nice to
 282              have.  */
 283
 284           if (s->filepos < 0)
 285             (*_bfd_error_handler)
 286               (_("Warning: Writing section `%s' to huge (ie negative) file offset 0x%lx."),
 287                bfd_get_section_name (abfd, s),
 288                (unsigned long) s->filepos);
 289         }
 290
 291       abfd->output_has_begun = TRUE;
 292     }
 293
 294   /* We don't want to output anything for a section that is neither
 295      loaded nor allocated.  The contents of such a section are not
 296      meaningful in the binary format.  */
 297   if ((sec->flags & (SEC_LOAD | SEC_ALLOC)) == 0)
 298     return TRUE;
 299   if ((sec->flags & SEC_NEVER_LOAD) != 0)
 300     return TRUE;
 301
 302   return _bfd_generic_set_section_contents (abfd, sec, data, offset, size);
 303 }
 304
 305 /* No space is required for header information.  */
 306
 307 static int
 308 binary_sizeof_headers (bfd *abfd ATTRIBUTE_UNUSED,
 309                        bfd_boolean exec ATTRIBUTE_UNUSED)
 310 {
 311   return 0;
 312 }
 313
 314 #define binary_bfd_get_relocated_section_contents  bfd_generic_get_relocated_section_contents
 315 #define binary_bfd_relax_section                   bfd_generic_relax_section
 316 #define binary_bfd_gc_sections                     bfd_generic_gc_sections
 317 #define binary_bfd_merge_sections                  bfd_generic_merge_sections
 318 #define binary_bfd_is_group_section                bfd_generic_is_group_section
 319 #define binary_bfd_discard_group                   bfd_generic_discard_group
 320 #define binary_section_already_linked             _bfd_generic_section_already_linked
 321 #define binary_bfd_link_hash_table_create         _bfd_generic_link_hash_table_create
 322 #define binary_bfd_link_hash_table_free           _bfd_generic_link_hash_table_free
 323 #define binary_bfd_link_just_syms                 _bfd_generic_link_just_syms
 324 #define binary_bfd_link_add_symbols               _bfd_generic_link_add_symbols
 325 #define binary_bfd_final_link                     _bfd_generic_final_link
 326 #define binary_bfd_link_split_section             _bfd_generic_link_split_section
 327 #define binary_get_section_contents_in_window     _bfd_generic_get_section_contents_in_window
 328
 329 const bfd_target binary_vec =
 330 {
 331   "binary",                     /* name */
 332   bfd_target_unknown_flavour,   /* flavour */
 333   BFD_ENDIAN_UNKNOWN,           /* byteorder */
 334   BFD_ENDIAN_UNKNOWN,           /* header_byteorder */
 335   EXEC_P,                       /* object_flags */
 336   (SEC_ALLOC | SEC_LOAD | SEC_READONLY | SEC_CODE | SEC_DATA
 337    | SEC_ROM | SEC_HAS_CONTENTS), /* section_flags */
 338   0,                            /* symbol_leading_char */
 339   ' ',                          /* ar_pad_char */
 340   16,                           /* ar_max_namelen */
 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,   /* data */
 344   bfd_getb64, bfd_getb_signed_64, bfd_putb64,
 345   bfd_getb32, bfd_getb_signed_32, bfd_putb32,
 346   bfd_getb16, bfd_getb_signed_16, bfd_putb16,   /* hdrs */
 347   {                             /* bfd_check_format */
 348     _bfd_dummy_target,
 349     binary_object_p,
 350     _bfd_dummy_target,
 351     _bfd_dummy_target,
 352   },
 353   {                             /* bfd_set_format */
 354     bfd_false,
 355     binary_mkobject,
 356     bfd_false,
 357     bfd_false,
 358   },
 359   {                             /* bfd_write_contents */
 360     bfd_false,
 361     bfd_true,
 362     bfd_false,
 363     bfd_false,
 364   },
 365
 366   BFD_JUMP_TABLE_GENERIC (binary),
 367   BFD_JUMP_TABLE_COPY (_bfd_generic),
 368   BFD_JUMP_TABLE_CORE (_bfd_nocore),
 369   BFD_JUMP_TABLE_ARCHIVE (_bfd_noarchive),
 370   BFD_JUMP_TABLE_SYMBOLS (binary),
 371   BFD_JUMP_TABLE_RELOCS (binary),
 372   BFD_JUMP_TABLE_WRITE (binary),
 373   BFD_JUMP_TABLE_LINK (binary),
 374   BFD_JUMP_TABLE_DYNAMIC (_bfd_nodynamic),
 375
 376   NULL,
 377
 378   NULL
 379 };