bfd/binary.c

   1 /* BFD back-end for binary objects.
   2    Copyright (C) 1994-2020 Free Software Foundation, Inc.
   3    Written by Ian Lance Taylor, Cygnus Support, <ian@cygnus.com>
   4
   5    This file is part of BFD, the Binary File Descriptor library.
   6
   7    This program is free software; you can redistribute it and/or modify
   8    it under the terms of the GNU General Public License as published by
   9    the Free Software Foundation; either version 3 of the License, or
  10    (at your option) any later version.
  11
  12    This program is distributed in the hope that it will be useful,
  13    but WITHOUT ANY WARRANTY; without even the implied warranty of
  14    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  15    GNU General Public License for more details.
  16
  17    You should have received a copy of the GNU General Public License
  18    along with this program; if not, write to the Free Software
  19    Foundation, Inc., 51 Franklin Street - Fifth Floor, Boston,
  20    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 "sysdep.h"
  36 #include "bfd.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 /* Create a binary object.  Invoked via bfd_set_format.  */
  45
  46 static bfd_boolean
  47 binary_mkobject (bfd *abfd ATTRIBUTE_UNUSED)
  48 {
  49   return TRUE;
  50 }
  51
  52 /* Any file may be considered to be a binary file, provided the target
  53    was not defaulted.  That is, it must be explicitly specified as
  54    being binary.  */
  55
  56 static bfd_cleanup
  57 binary_object_p (bfd *abfd)
  58 {
  59   struct stat statbuf;
  60   asection *sec;
  61   flagword flags;
  62
  63   if (abfd->target_defaulted)
  64     {
  65       bfd_set_error (bfd_error_wrong_format);
  66       return NULL;
  67     }
  68
  69   abfd->symcount = BIN_SYMS;
  70
  71   /* Find the file size.  */
  72   if (bfd_stat (abfd, &statbuf) < 0)
  73     {
  74       bfd_set_error (bfd_error_system_call);
  75       return NULL;
  76     }
  77
  78   /* One data section.  */
  79   flags = SEC_ALLOC | SEC_LOAD | SEC_DATA | SEC_HAS_CONTENTS;
  80   sec = bfd_make_section_with_flags (abfd, ".data", flags);
  81   if (sec == NULL)
  82     return NULL;
  83   sec->vma = 0;
  84   sec->size = statbuf.st_size;
  85   sec->filepos = 0;
  86
  87   abfd->tdata.any = (void *) sec;
  88
  89   return _bfd_no_cleanup;
  90 }
  91
  92 #define binary_close_and_cleanup     _bfd_generic_close_and_cleanup
  93 #define binary_bfd_free_cached_info  _bfd_generic_bfd_free_cached_info
  94 #define binary_new_section_hook      _bfd_generic_new_section_hook
  95
  96 /* Get contents of the only section.  */
  97
  98 static bfd_boolean
  99 binary_get_section_contents (bfd *abfd,
 100                              asection *section ATTRIBUTE_UNUSED,
 101                              void * location,
 102                              file_ptr offset,
 103                              bfd_size_type count)
 104 {
 105   if (bfd_seek (abfd, offset, SEEK_SET) != 0
 106       || bfd_bread (location, count, abfd) != count)
 107     return FALSE;
 108   return TRUE;
 109 }
 110
 111 /* Return the amount of memory needed to read the symbol table.  */
 112
 113 static long
 114 binary_get_symtab_upper_bound (bfd *abfd ATTRIBUTE_UNUSED)
 115 {
 116   return (BIN_SYMS + 1) * sizeof (asymbol *);
 117 }
 118
 119 /* Create a symbol name based on the bfd's filename.  */
 120
 121 static char *
 122 mangle_name (bfd *abfd, char *suffix)
 123 {
 124   bfd_size_type size;
 125   char *buf;
 126   char *p;
 127
 128   size = (strlen (bfd_get_filename (abfd))
 129           + strlen (suffix)
 130           + sizeof "_binary__");
 131
 132   buf = (char *) bfd_alloc (abfd, size);
 133   if (buf == NULL)
 134     return "";
 135
 136   sprintf (buf, "_binary_%s_%s", bfd_get_filename (abfd), suffix);
 137
 138   /* Change any non-alphanumeric characters to underscores.  */
 139   for (p = buf; *p; p++)
 140     if (! ISALNUM (*p))
 141       *p = '_';
 142
 143   return buf;
 144 }
 145
 146 /* Return the symbol table.  */
 147
 148 static long
 149 binary_canonicalize_symtab (bfd *abfd, asymbol **alocation)
 150 {
 151   asection *sec = (asection *) abfd->tdata.any;
 152   asymbol *syms;
 153   unsigned int i;
 154   size_t amt = BIN_SYMS * sizeof (asymbol);
 155
 156   syms = (asymbol *) bfd_alloc (abfd, amt);
 157   if (syms == NULL)
 158     return -1;
 159
 160   /* Start symbol.  */
 161   syms[0].the_bfd = abfd;
 162   syms[0].name = mangle_name (abfd, "start");
 163   syms[0].value = 0;
 164   syms[0].flags = BSF_GLOBAL;
 165   syms[0].section = sec;
 166   syms[0].udata.p = NULL;
 167
 168   /* End symbol.  */
 169   syms[1].the_bfd = abfd;
 170   syms[1].name = mangle_name (abfd, "end");
 171   syms[1].value = sec->size;
 172   syms[1].flags = BSF_GLOBAL;
 173   syms[1].section = sec;
 174   syms[1].udata.p = NULL;
 175
 176   /* Size symbol.  */
 177   syms[2].the_bfd = abfd;
 178   syms[2].name = mangle_name (abfd, "size");
 179   syms[2].value = sec->size;
 180   syms[2].flags = BSF_GLOBAL;
 181   syms[2].section = bfd_abs_section_ptr;
 182   syms[2].udata.p = NULL;
 183
 184   for (i = 0; i < BIN_SYMS; i++)
 185     *alocation++ = syms++;
 186   *alocation = NULL;
 187
 188   return BIN_SYMS;
 189 }
 190
 191 #define binary_make_empty_symbol  _bfd_generic_make_empty_symbol
 192 #define binary_print_symbol       _bfd_nosymbols_print_symbol
 193 #define binary_get_symbol_version_string \
 194   _bfd_nosymbols_get_symbol_version_string
 195
 196 /* Get information about a symbol.  */
 197
 198 static void
 199 binary_get_symbol_info (bfd *ignore_abfd ATTRIBUTE_UNUSED,
 200                         asymbol *symbol,
 201                         symbol_info *ret)
 202 {
 203   bfd_symbol_info (symbol, ret);
 204 }
 205
 206 #define binary_bfd_is_local_label_name      bfd_generic_is_local_label_name
 207 #define binary_get_lineno                  _bfd_nosymbols_get_lineno
 208 #define binary_find_nearest_line           _bfd_nosymbols_find_nearest_line
 209 #define binary_find_line                   _bfd_nosymbols_find_line
 210 #define binary_find_inliner_info           _bfd_nosymbols_find_inliner_info
 211 #define binary_bfd_make_debug_symbol       _bfd_nosymbols_bfd_make_debug_symbol
 212 #define binary_read_minisymbols            _bfd_generic_read_minisymbols
 213 #define binary_minisymbol_to_symbol        _bfd_generic_minisymbol_to_symbol
 214 #define binary_bfd_is_target_special_symbol _bfd_bool_bfd_asymbol_false
 215
 216 /* Set the architecture of a binary file.  */
 217 #define binary_set_arch_mach _bfd_generic_set_arch_mach
 218
 219 /* Write section contents of a binary file.  */
 220
 221 static bfd_boolean
 222 binary_set_section_contents (bfd *abfd,
 223                              asection *sec,
 224                              const void * data,
 225                              file_ptr offset,
 226                              bfd_size_type size)
 227 {
 228   if (size == 0)
 229     return TRUE;
 230
 231   if (! abfd->output_has_begun)
 232     {
 233       bfd_boolean found_low;
 234       bfd_vma low;
 235       asection *s;
 236
 237       /* The lowest section LMA sets the virtual address of the start
 238          of the file.  We use this to set the file position of all the
 239          sections.  */
 240       found_low = FALSE;
 241       low = 0;
 242       for (s = abfd->sections; s != NULL; s = s->next)
 243         if (((s->flags
 244               & (SEC_HAS_CONTENTS | SEC_LOAD | SEC_ALLOC | SEC_NEVER_LOAD))
 245              == (SEC_HAS_CONTENTS | SEC_LOAD | SEC_ALLOC))
 246             && (s->size > 0)
 247             && (! found_low || s->lma < low))
 248           {
 249             low = s->lma;
 250             found_low = TRUE;
 251           }
 252
 253       for (s = abfd->sections; s != NULL; s = s->next)
 254         {
 255           unsigned int opb = bfd_octets_per_byte (abfd, s);
 256
 257           s->filepos = (s->lma - low) * opb;
 258
 259           /* Skip following warning check for sections that will not
 260              occupy file space.  */
 261           if ((s->flags
 262                & (SEC_HAS_CONTENTS | SEC_ALLOC | SEC_NEVER_LOAD))
 263               != (SEC_HAS_CONTENTS | SEC_ALLOC)
 264               || (s->size == 0))
 265             continue;
 266
 267           /* If attempting to generate a binary file from a bfd with
 268              LMA's all over the place, huge (sparse?) binary files may
 269              result.  This condition attempts to detect this situation
 270              and print a warning.  Better heuristics would be nice to
 271              have.  */
 272
 273           if (s->filepos < 0)
 274             _bfd_error_handler
 275               /* xgettext:c-format */
 276               (_("warning: writing section `%pA' at huge (ie negative) "
 277                  "file offset"),
 278                s);
 279         }
 280
 281       abfd->output_has_begun = TRUE;
 282     }
 283
 284   /* We don't want to output anything for a section that is neither
 285      loaded nor allocated.  The contents of such a section are not
 286      meaningful in the binary format.  */
 287   if ((sec->flags & (SEC_LOAD | SEC_ALLOC)) == 0)
 288     return TRUE;
 289   if ((sec->flags & SEC_NEVER_LOAD) != 0)
 290     return TRUE;
 291
 292   return _bfd_generic_set_section_contents (abfd, sec, data, offset, size);
 293 }
 294
 295 /* No space is required for header information.  */
 296
 297 static int
 298 binary_sizeof_headers (bfd *abfd ATTRIBUTE_UNUSED,
 299                        struct bfd_link_info *info ATTRIBUTE_UNUSED)
 300 {
 301   return 0;
 302 }
 303
 304 #define binary_bfd_get_relocated_section_contents  bfd_generic_get_relocated_section_contents
 305 #define binary_bfd_relax_section                   bfd_generic_relax_section
 306 #define binary_bfd_gc_sections                     bfd_generic_gc_sections
 307 #define binary_bfd_lookup_section_flags            bfd_generic_lookup_section_flags
 308 #define binary_bfd_merge_sections                  bfd_generic_merge_sections
 309 #define binary_bfd_is_group_section                bfd_generic_is_group_section
 310 #define binary_bfd_group_name                      bfd_generic_group_name
 311 #define binary_bfd_discard_group                   bfd_generic_discard_group
 312 #define binary_section_already_linked             _bfd_generic_section_already_linked
 313 #define binary_bfd_define_common_symbol            bfd_generic_define_common_symbol
 314 #define binary_bfd_link_hide_symbol                _bfd_generic_link_hide_symbol
 315 #define binary_bfd_define_start_stop               bfd_generic_define_start_stop
 316 #define binary_bfd_link_hash_table_create         _bfd_generic_link_hash_table_create
 317 #define binary_bfd_link_just_syms                 _bfd_generic_link_just_syms
 318 #define binary_bfd_copy_link_hash_symbol_type     _bfd_generic_copy_link_hash_symbol_type
 319 #define binary_bfd_link_add_symbols               _bfd_generic_link_add_symbols
 320 #define binary_bfd_final_link                     _bfd_generic_final_link
 321 #define binary_bfd_link_split_section             _bfd_generic_link_split_section
 322 #define binary_get_section_contents_in_window     _bfd_generic_get_section_contents_in_window
 323 #define binary_bfd_link_check_relocs              _bfd_generic_link_check_relocs
 324
 325 const bfd_target binary_vec =
 326 {
 327   "binary",                     /* name */
 328   bfd_target_unknown_flavour,   /* flavour */
 329   BFD_ENDIAN_UNKNOWN,           /* byteorder */
 330   BFD_ENDIAN_UNKNOWN,           /* header_byteorder */
 331   EXEC_P,                       /* object_flags */
 332   (SEC_ALLOC | SEC_LOAD | SEC_READONLY | SEC_CODE | SEC_DATA
 333    | SEC_ROM | SEC_HAS_CONTENTS), /* section_flags */
 334   0,                            /* symbol_leading_char */
 335   ' ',                          /* ar_pad_char */
 336   16,                           /* ar_max_namelen */
 337   255,                          /* match priority.  */
 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_bool_bfd_false_error,
 352     binary_mkobject,
 353     _bfd_bool_bfd_false_error,
 354     _bfd_bool_bfd_false_error,
 355   },
 356   {                             /* bfd_write_contents */
 357     _bfd_bool_bfd_false_error,
 358     _bfd_bool_bfd_true,
 359     _bfd_bool_bfd_false_error,
 360     _bfd_bool_bfd_false_error,
 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 };