bfd/i386msdos.c

   1 /* BFD back-end for MS-DOS executables.
   2    Copyright (C) 1990-2017 Free Software Foundation, Inc.
   3    Written by Bryan Ford of the University of Utah.
   4
   5    Contributed by the Center for Software Science at the
   6    University of Utah (pa-gdb-bugs@cs.utah.edu).
   7
   8    This file is part of BFD, the Binary File Descriptor library.
   9
  10    This program is free software; you can redistribute it and/or modify
  11    it under the terms of the GNU General Public License as published by
  12    the Free Software Foundation; either version 3 of the License, or
  13    (at your option) any later version.
  14
  15    This program is distributed in the hope that it will be useful,
  16    but WITHOUT ANY WARRANTY; without even the implied warranty of
  17    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  18    GNU General Public License for more details.
  19
  20    You should have received a copy of the GNU General Public License
  21    along with this program; if not, write to the Free Software
  22    Foundation, Inc., 51 Franklin Street - Fifth Floor, Boston,
  23    MA 02110-1301, USA.  */
  24
  25
  26 #include "sysdep.h"
  27 #include "bfd.h"
  28 #include "libbfd.h"
  29 #include "libaout.h"
  30
  31 #define EXE_MAGIC       0x5a4d
  32 #define EXE_LOAD_HIGH   0x0000
  33 #define EXE_LOAD_LOW    0xffff
  34 #define EXE_PAGE_SIZE   512
  35
  36 static int
  37 msdos_sizeof_headers (bfd *abfd ATTRIBUTE_UNUSED,
  38                       struct bfd_link_info *info ATTRIBUTE_UNUSED)
  39 {
  40   return 0;
  41 }
  42
  43 static bfd_boolean
  44 msdos_write_object_contents (bfd *abfd)
  45 {
  46   static char hdr[EXE_PAGE_SIZE];
  47   file_ptr outfile_size = sizeof(hdr);
  48   bfd_vma high_vma = 0;
  49   asection *sec;
  50
  51   /* Find the total size of the program on disk and in memory.  */
  52   for (sec = abfd->sections; sec != (asection *) NULL; sec = sec->next)
  53     {
  54       if (sec->size == 0)
  55         continue;
  56       if (bfd_get_section_flags (abfd, sec) & SEC_ALLOC)
  57         {
  58           bfd_vma sec_vma = bfd_get_section_vma (abfd, sec) + sec->size;
  59           if (sec_vma > high_vma)
  60             high_vma = sec_vma;
  61         }
  62       if (bfd_get_section_flags (abfd, sec) & SEC_LOAD)
  63         {
  64           file_ptr sec_end = (sizeof (hdr)
  65                               + bfd_get_section_vma (abfd, sec)
  66                               + sec->size);
  67           if (sec_end > outfile_size)
  68             outfile_size = sec_end;
  69         }
  70     }
  71
  72   /* Make sure the program isn't too big.  */
  73   if (high_vma > (bfd_vma)0xffff)
  74     {
  75       bfd_set_error(bfd_error_file_too_big);
  76       return FALSE;
  77     }
  78
  79   /* Constants.  */
  80   H_PUT_16 (abfd, EXE_MAGIC, &hdr[0]);
  81   H_PUT_16 (abfd, EXE_PAGE_SIZE / 16, &hdr[8]);
  82   H_PUT_16 (abfd, EXE_LOAD_LOW, &hdr[12]);
  83   H_PUT_16 (abfd, 0x3e, &hdr[24]);
  84   H_PUT_16 (abfd, 0x0001, &hdr[28]); /* XXX??? */
  85   H_PUT_16 (abfd, 0x30fb, &hdr[30]); /* XXX??? */
  86   H_PUT_16 (abfd, 0x726a, &hdr[32]); /* XXX??? */
  87
  88   /* Bytes in last page (0 = full page).  */
  89   H_PUT_16 (abfd, outfile_size & (EXE_PAGE_SIZE - 1), &hdr[2]);
  90
  91   /* Number of pages.  */
  92   H_PUT_16 (abfd, (outfile_size + EXE_PAGE_SIZE - 1) / EXE_PAGE_SIZE, &hdr[4]);
  93
  94   /* Set the initial stack pointer to the end of the bss.
  95      The program's crt0 code must relocate it to a real stack.  */
  96   H_PUT_16 (abfd, high_vma, &hdr[16]);
  97
  98   if (bfd_seek (abfd, (file_ptr) 0, SEEK_SET) != 0
  99       || bfd_bwrite (hdr, (bfd_size_type) sizeof(hdr), abfd) != sizeof(hdr))
 100     return FALSE;
 101
 102   return TRUE;
 103 }
 104
 105 static bfd_boolean
 106 msdos_set_section_contents (bfd *abfd,
 107                             sec_ptr section,
 108                             const void *location,
 109                             file_ptr offset,
 110                             bfd_size_type count)
 111 {
 112
 113   if (count == 0)
 114     return TRUE;
 115
 116   section->filepos = EXE_PAGE_SIZE + bfd_get_section_vma (abfd, section);
 117
 118   if (bfd_get_section_flags (abfd, section) & SEC_LOAD)
 119     {
 120       if (bfd_seek (abfd, section->filepos + offset, SEEK_SET) != 0
 121           || bfd_bwrite (location, count, abfd) != count)
 122         return FALSE;
 123     }
 124
 125   return TRUE;
 126 }
 127
 128
 129
 130 #define msdos_mkobject aout_32_mkobject
 131 #define msdos_make_empty_symbol aout_32_make_empty_symbol
 132 #define msdos_bfd_reloc_type_lookup aout_32_reloc_type_lookup
 133 #define msdos_bfd_reloc_name_lookup aout_32_reloc_name_lookup
 134
 135 #define msdos_close_and_cleanup _bfd_generic_close_and_cleanup
 136 #define msdos_bfd_free_cached_info _bfd_generic_bfd_free_cached_info
 137 #define msdos_new_section_hook _bfd_generic_new_section_hook
 138 #define msdos_get_section_contents _bfd_generic_get_section_contents
 139 #define msdos_get_section_contents_in_window \
 140   _bfd_generic_get_section_contents_in_window
 141 #define msdos_bfd_get_relocated_section_contents \
 142   bfd_generic_get_relocated_section_contents
 143 #define msdos_bfd_relax_section bfd_generic_relax_section
 144 #define msdos_bfd_gc_sections bfd_generic_gc_sections
 145 #define msdos_bfd_lookup_section_flags bfd_generic_lookup_section_flags
 146 #define msdos_bfd_merge_sections bfd_generic_merge_sections
 147 #define msdos_bfd_is_group_section bfd_generic_is_group_section
 148 #define msdos_bfd_discard_group bfd_generic_discard_group
 149 #define msdos_section_already_linked \
 150   _bfd_generic_section_already_linked
 151 #define msdos_bfd_define_common_symbol bfd_generic_define_common_symbol
 152 #define msdos_bfd_define_start_stop bfd_generic_define_start_stop
 153 #define msdos_bfd_link_hash_table_create _bfd_generic_link_hash_table_create
 154 #define msdos_bfd_link_add_symbols _bfd_generic_link_add_symbols
 155 #define msdos_bfd_link_just_syms _bfd_generic_link_just_syms
 156 #define msdos_bfd_copy_link_hash_symbol_type \
 157   _bfd_generic_copy_link_hash_symbol_type
 158 #define msdos_bfd_final_link _bfd_generic_final_link
 159 #define msdos_bfd_link_split_section _bfd_generic_link_split_section
 160 #define msdos_set_arch_mach _bfd_generic_set_arch_mach
 161 #define msdos_bfd_link_check_relocs _bfd_generic_link_check_relocs
 162
 163 #define msdos_get_symtab_upper_bound _bfd_nosymbols_get_symtab_upper_bound
 164 #define msdos_canonicalize_symtab _bfd_nosymbols_canonicalize_symtab
 165 #define msdos_print_symbol _bfd_nosymbols_print_symbol
 166 #define msdos_get_symbol_info _bfd_nosymbols_get_symbol_info
 167 #define msdos_get_symbol_version_string \
 168   _bfd_nosymbols_get_symbol_version_string
 169 #define msdos_find_nearest_line _bfd_nosymbols_find_nearest_line
 170 #define msdos_find_line _bfd_nosymbols_find_line
 171 #define msdos_find_inliner_info _bfd_nosymbols_find_inliner_info
 172 #define msdos_get_lineno _bfd_nosymbols_get_lineno
 173 #define msdos_bfd_is_target_special_symbol ((bfd_boolean (*) (bfd *, asymbol *)) bfd_false)
 174 #define msdos_bfd_is_local_label_name _bfd_nosymbols_bfd_is_local_label_name
 175 #define msdos_bfd_make_debug_symbol _bfd_nosymbols_bfd_make_debug_symbol
 176 #define msdos_read_minisymbols _bfd_nosymbols_read_minisymbols
 177 #define msdos_minisymbol_to_symbol _bfd_nosymbols_minisymbol_to_symbol
 178
 179 #define msdos_canonicalize_reloc _bfd_norelocs_canonicalize_reloc
 180 #define msdos_set_reloc _bfd_norelocs_set_reloc
 181 #define msdos_get_reloc_upper_bound _bfd_norelocs_get_reloc_upper_bound
 182 #define msdos_32_bfd_link_split_section  _bfd_generic_link_split_section
 183
 184 const bfd_target i386_msdos_vec =
 185   {
 186     "msdos",                    /* name */
 187     bfd_target_msdos_flavour,
 188     BFD_ENDIAN_LITTLE,          /* target byte order */
 189     BFD_ENDIAN_LITTLE,          /* target headers byte order */
 190     (EXEC_P),                   /* object flags */
 191     (SEC_CODE | SEC_DATA | SEC_HAS_CONTENTS
 192      | SEC_ALLOC | SEC_LOAD),   /* section flags */
 193     0,                          /* leading underscore */
 194     ' ',                                /* ar_pad_char */
 195     16,                         /* ar_max_namelen */
 196     0,                          /* match priority.  */
 197     bfd_getl64, bfd_getl_signed_64, bfd_putl64,
 198     bfd_getl32, bfd_getl_signed_32, bfd_putl32,
 199     bfd_getl16, bfd_getl_signed_16, bfd_putl16, /* data */
 200     bfd_getl64, bfd_getl_signed_64, bfd_putl64,
 201     bfd_getl32, bfd_getl_signed_32, bfd_putl32,
 202     bfd_getl16, bfd_getl_signed_16, bfd_putl16, /* hdrs */
 203
 204     {
 205       _bfd_dummy_target,
 206       _bfd_dummy_target,                /* bfd_check_format */
 207       _bfd_dummy_target,
 208       _bfd_dummy_target,
 209     },
 210     {
 211       bfd_false,
 212       msdos_mkobject,
 213       _bfd_generic_mkarchive,
 214       bfd_false,
 215     },
 216     {                           /* bfd_write_contents */
 217       bfd_false,
 218       msdos_write_object_contents,
 219       _bfd_write_archive_contents,
 220       bfd_false,
 221     },
 222
 223     BFD_JUMP_TABLE_GENERIC (msdos),
 224     BFD_JUMP_TABLE_COPY (_bfd_generic),
 225     BFD_JUMP_TABLE_CORE (_bfd_nocore),
 226     BFD_JUMP_TABLE_ARCHIVE (_bfd_noarchive),
 227     BFD_JUMP_TABLE_SYMBOLS (msdos),
 228     BFD_JUMP_TABLE_RELOCS (msdos),
 229     BFD_JUMP_TABLE_WRITE (msdos),
 230     BFD_JUMP_TABLE_LINK (msdos),
 231     BFD_JUMP_TABLE_DYNAMIC (_bfd_nodynamic),
 232
 233     NULL,
 234
 235     NULL
 236   };
 237
 238