/* BFD back-end for MS-DOS executables.

   Copyright (C) 1990-2025 Free Software Foundation, Inc.

   Written by Bryan Ford of the University of Utah.

   Contributed by the Center for Software Science at the

   University of Utah (pa-gdb-bugs@cs.utah.edu).

   This file is part of BFD, the Binary File Descriptor library.

   This program is free software; you can redistribute it and/or modify

   it under the terms of the GNU General Public License as published by

   the Free Software Foundation; either version 3 of the License, or

   (at your option) any later version.

   This program is distributed in the hope that it will be useful,

   but WITHOUT ANY WARRANTY; without even the implied warranty of

   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the

   GNU General Public License for more details.

   You should have received a copy of the GNU General Public License

   along with this program; if not, write to the Free Software

   Foundation, Inc., 51 Franklin Street - Fifth Floor, Boston,

   MA 02110-1301, USA.  */

#include "sysdep.h"

#include "bfd.h"

#include "libbfd.h"

#include "libaout.h"

#include "coff/msdos.h"

#define EXE_LOAD_HIGH 0x0000

#define EXE_LOAD_LOW  0xffff

#define EXE_PAGE_SIZE 512

static bool

msdos_mkobject (bfd *abfd)

{

  bfd_default_set_arch_mach (abfd, bfd_arch_i386, bfd_mach_i386_i8086);

  return aout_32_mkobject (abfd);

}

static bfd_cleanup

msdos_object_p (bfd *abfd)

{

  struct external_DOS_hdr hdr;

  bfd_byte buffer[2];

  asection *section;

  bfd_size_type size;

  if (bfd_seek (abfd, 0, SEEK_SET) != 0

      || (size = bfd_read (&hdr, sizeof (hdr), abfd)) + 1 < DOS_HDR_SIZE + 1)

    {

      if (bfd_get_error () != bfd_error_system_call)

  bfd_set_error (bfd_error_wrong_format);

      return NULL;

    }

  if (H_GET_16 (abfd, hdr.e_magic) != IMAGE_DOS_SIGNATURE)

    {

      bfd_set_error (bfd_error_wrong_format);

      return NULL;

    }

  /* Check that this isn't actually a PE, NE, or LE file. If it is, the

     e_lfanew field will be valid and point to a header beginning with one of

     the relevant signatures.  If not, e_lfanew might point to anything, so

     don't bail if we can't read there.  */

  if (size < offsetof (struct external_DOS_hdr, e_lfanew) + 4

      || H_GET_16 (abfd, hdr.e_cparhdr) < 4)

    ;

  else if (bfd_seek (abfd, H_GET_32 (abfd, hdr.e_lfanew), SEEK_SET) != 0

     || bfd_read (buffer, 2, abfd) != 2)

    {

      if (bfd_get_error () == bfd_error_system_call)

  return NULL;

    }

  else

    {

      if (H_GET_16 (abfd, buffer) == IMAGE_NT_SIGNATURE

    || H_GET_16 (abfd, buffer) == IMAGE_OS2_SIGNATURE

    || H_GET_16 (abfd, buffer) == IMAGE_OS2_SIGNATURE_LE

    || H_GET_16 (abfd, buffer) == IMAGE_OS2_SIGNATURE_LX)

  {

    bfd_set_error (bfd_error_wrong_format);

    return NULL;

  }

    }

  if (!msdos_mkobject (abfd))

    return NULL;

  abfd->flags = EXEC_P;

  abfd->start_address = H_GET_16 (abfd, hdr.e_ip);

  section = bfd_make_section (abfd, ".text");

  if (section == NULL)

    return NULL;

  section->flags = (SEC_ALLOC | SEC_LOAD | SEC_CODE | SEC_HAS_CONTENTS);

  section->filepos = H_GET_16 (abfd, hdr.e_cparhdr) * 16;

  size = (H_GET_16 (abfd, hdr.e_cp) - 1) * EXE_PAGE_SIZE - section->filepos;

  size += H_GET_16 (abfd, hdr.e_cblp);

  /* Check that the size is valid.  */

  if (bfd_seek (abfd, section->filepos + size, SEEK_SET) != 0)

    {

      if (bfd_get_error () != bfd_error_system_call)

  bfd_set_error (bfd_error_wrong_format);

      return NULL;

    }

  bfd_set_section_size (section, size);

  section->alignment_power = 4;

  return _bfd_no_cleanup;

}

static int

msdos_sizeof_headers (bfd *abfd ATTRIBUTE_UNUSED,

          struct bfd_link_info *info ATTRIBUTE_UNUSED)

{

  return 0;

}

static bool

msdos_write_object_contents (bfd *abfd)

{

  static char hdr[EXE_PAGE_SIZE];

  file_ptr outfile_size = sizeof(hdr);

  bfd_vma high_vma = 0;

  asection *sec;

  /* Find the total size of the program on disk and in memory.  */

  for (sec = abfd->sections; sec != (asection *) NULL; sec = sec->next)

    {

      if (sec->size == 0)

  continue;

      if (bfd_section_flags (sec) & SEC_ALLOC)

  {

    bfd_vma sec_vma = bfd_section_vma (sec) + sec->size;

    if (sec_vma > high_vma)

      high_vma = sec_vma;

  }

      if (bfd_section_flags (sec) & SEC_LOAD)

  {

    file_ptr sec_end = (sizeof (hdr)

            + bfd_section_vma (sec)

            + sec->size);

    if (sec_end > outfile_size)

      outfile_size = sec_end;

  }

    }

  /* Make sure the program isn't too big.  */

  if (high_vma > (bfd_vma)0xffff)

    {

      bfd_set_error(bfd_error_file_too_big);

      return false;

    }

  /* Constants.  */

  H_PUT_16 (abfd, IMAGE_DOS_SIGNATURE, &hdr[0]);

  H_PUT_16 (abfd, EXE_PAGE_SIZE / 16, &hdr[8]);

  H_PUT_16 (abfd, EXE_LOAD_LOW, &hdr[12]);

  H_PUT_16 (abfd, 0x3e, &hdr[24]);

  H_PUT_16 (abfd, 0x0001, &hdr[28]); /* XXX??? */

  H_PUT_16 (abfd, 0x30fb, &hdr[30]); /* XXX??? */

  H_PUT_16 (abfd, 0x726a, &hdr[32]); /* XXX??? */

  /* Bytes in last page (0 = full page).  */

  H_PUT_16 (abfd, outfile_size & (EXE_PAGE_SIZE - 1), &hdr[2]);

  /* Number of pages.  */

  H_PUT_16 (abfd, (outfile_size + EXE_PAGE_SIZE - 1) / EXE_PAGE_SIZE, &hdr[4]);

  /* Set the initial stack pointer to the end of the bss.

     The program's crt0 code must relocate it to a real stack.  */

  H_PUT_16 (abfd, high_vma, &hdr[16]);

  if (bfd_seek (abfd, 0, SEEK_SET) != 0

      || bfd_write (hdr, sizeof (hdr), abfd) != sizeof (hdr))

    return false;

  return true;

}

static bool

msdos_set_section_contents (bfd *abfd,

          sec_ptr section,

          const void *location,

          file_ptr offset,

          bfd_size_type count)

{

  if (count == 0)

    return true;

  section->filepos = EXE_PAGE_SIZE + bfd_section_vma (section);

  if (bfd_section_flags (section) & SEC_LOAD)

    {

      if (bfd_seek (abfd, section->filepos + offset, SEEK_SET) != 0

    || bfd_write (location, count, abfd) != count)

  return false;

    }

  return true;

}

#define msdos_make_empty_symbol aout_32_make_empty_symbol

#define msdos_bfd_reloc_type_lookup aout_32_reloc_type_lookup

#define msdos_bfd_reloc_name_lookup aout_32_reloc_name_lookup

#define msdos_close_and_cleanup _bfd_generic_close_and_cleanup

#define msdos_bfd_free_cached_info _bfd_generic_bfd_free_cached_info

#define msdos_new_section_hook _bfd_generic_new_section_hook

#define msdos_get_section_contents _bfd_generic_get_section_contents

#define msdos_bfd_get_relocated_section_contents \

  bfd_generic_get_relocated_section_contents

#define msdos_bfd_relax_section bfd_generic_relax_section

#define msdos_bfd_gc_sections bfd_generic_gc_sections

#define msdos_bfd_lookup_section_flags bfd_generic_lookup_section_flags

#define msdos_bfd_merge_sections bfd_generic_merge_sections

#define msdos_bfd_is_group_section bfd_generic_is_group_section

#define msdos_bfd_group_name bfd_generic_group_name

#define msdos_bfd_discard_group bfd_generic_discard_group

#define msdos_section_already_linked \

  _bfd_generic_section_already_linked

#define msdos_bfd_define_common_symbol bfd_generic_define_common_symbol

#define msdos_bfd_link_hide_symbol _bfd_generic_link_hide_symbol

#define msdos_bfd_define_start_stop bfd_generic_define_start_stop

#define msdos_bfd_link_hash_table_create _bfd_generic_link_hash_table_create

#define msdos_bfd_link_add_symbols _bfd_generic_link_add_symbols

#define msdos_bfd_link_just_syms _bfd_generic_link_just_syms

#define msdos_bfd_copy_link_hash_symbol_type \

  _bfd_generic_copy_link_hash_symbol_type

#define msdos_bfd_final_link _bfd_generic_final_link

#define msdos_bfd_link_split_section _bfd_generic_link_split_section

#define msdos_set_arch_mach _bfd_generic_set_arch_mach

#define msdos_bfd_link_check_relocs _bfd_generic_link_check_relocs

#define msdos_get_symtab_upper_bound _bfd_nosymbols_get_symtab_upper_bound

#define msdos_canonicalize_symtab _bfd_nosymbols_canonicalize_symtab

#define msdos_print_symbol _bfd_nosymbols_print_symbol

#define msdos_get_symbol_info _bfd_nosymbols_get_symbol_info

#define msdos_get_symbol_version_string \

  _bfd_nosymbols_get_symbol_version_string

#define msdos_find_nearest_line _bfd_nosymbols_find_nearest_line

#define msdos_find_nearest_line_with_alt _bfd_nosymbols_find_nearest_line_with_alt

#define msdos_find_line _bfd_nosymbols_find_line

#define msdos_find_inliner_info _bfd_nosymbols_find_inliner_info

#define msdos_get_lineno _bfd_nosymbols_get_lineno

#define msdos_bfd_is_target_special_symbol _bfd_bool_bfd_asymbol_false

#define msdos_bfd_is_local_label_name _bfd_nosymbols_bfd_is_local_label_name

#define msdos_bfd_make_debug_symbol _bfd_nosymbols_bfd_make_debug_symbol

#define msdos_read_minisymbols _bfd_nosymbols_read_minisymbols

#define msdos_minisymbol_to_symbol _bfd_nosymbols_minisymbol_to_symbol

#define msdos_canonicalize_reloc _bfd_norelocs_canonicalize_reloc

#define msdos_set_reloc _bfd_norelocs_set_reloc

#define msdos_get_reloc_upper_bound _bfd_norelocs_get_reloc_upper_bound

#define msdos_32_bfd_link_split_section  _bfd_generic_link_split_section

const bfd_target i386_msdos_vec =

  {

    "msdos",      /* name */

    bfd_target_msdos_flavour,

    BFD_ENDIAN_LITTLE,    /* target byte order */

    BFD_ENDIAN_LITTLE,    /* target headers byte order */

    (EXEC_P),     /* object flags */

    (SEC_CODE | SEC_DATA | SEC_HAS_CONTENTS

     | SEC_ALLOC | SEC_LOAD), /* section flags */

    0,        /* leading underscore */

    ' ',        /* ar_pad_char */

    16,       /* ar_max_namelen */

    0,        /* match priority.  */

    TARGET_KEEP_UNUSED_SECTION_SYMBOLS, /* keep unused section symbols.  */

    bfd_getl64, bfd_getl_signed_64, bfd_putl64,

    bfd_getl32, bfd_getl_signed_32, bfd_putl32,

    bfd_getl16, bfd_getl_signed_16, bfd_putl16, /* data */

    bfd_getl64, bfd_getl_signed_64, bfd_putl64,

    bfd_getl32, bfd_getl_signed_32, bfd_putl32,

    bfd_getl16, bfd_getl_signed_16, bfd_putl16, /* hdrs */

    {

      _bfd_dummy_target,

      msdos_object_p,   /* bfd_check_format */

      _bfd_dummy_target,

      _bfd_dummy_target,

    },

    {

      _bfd_bool_bfd_false_error,

      msdos_mkobject,

      _bfd_bool_bfd_false_error,

      _bfd_bool_bfd_false_error,

    },

    {       /* bfd_write_contents */

      _bfd_bool_bfd_false_error,

      msdos_write_object_contents,

      _bfd_bool_bfd_false_error,

      _bfd_bool_bfd_false_error,

    },

    BFD_JUMP_TABLE_GENERIC (msdos),

    BFD_JUMP_TABLE_COPY (_bfd_generic),

    BFD_JUMP_TABLE_CORE (_bfd_nocore),

    BFD_JUMP_TABLE_ARCHIVE (_bfd_noarchive),

    BFD_JUMP_TABLE_SYMBOLS (msdos),

    BFD_JUMP_TABLE_RELOCS (msdos),

    BFD_JUMP_TABLE_WRITE (msdos),

    BFD_JUMP_TABLE_LINK (msdos),

    BFD_JUMP_TABLE_DYNAMIC (_bfd_nodynamic),

    NULL,

    NULL

  };