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binutils-gdb/bfd/i386msdos.c

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/* BFD back-end for MS-DOS executables.
Copyright (C) 1990-2020 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 bfd_boolean
msdos_mkobject (bfd *abfd)
{
bfd_default_set_arch_mach (abfd, bfd_arch_i386, bfd_mach_i386_i8086);
return aout_32_mkobject (abfd);
}
static const bfd_target *
msdos_object_p (bfd *abfd)
{
struct external_DOS_hdr hdr;
bfd_byte buffer[2];
asection *section;
unsigned int size;
if (bfd_seek (abfd, (file_ptr) 0, SEEK_SET) != 0
|| bfd_bread (&hdr, (bfd_size_type) sizeof (hdr), abfd) < DOS_HDR_SIZE)
{
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 (H_GET_16 (abfd, hdr.e_cparhdr) < 4
|| bfd_seek (abfd, (file_ptr) H_GET_32 (abfd, hdr.e_lfanew), SEEK_SET) != 0
|| bfd_bread (buffer, (bfd_size_type) 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, (file_ptr) (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 abfd->xvec;
}
static int
msdos_sizeof_headers (bfd *abfd ATTRIBUTE_UNUSED,
struct bfd_link_info *info ATTRIBUTE_UNUSED)
{
return 0;
}
static bfd_boolean
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, (file_ptr) 0, SEEK_SET) != 0
|| bfd_bwrite (hdr, (bfd_size_type) sizeof(hdr), abfd) != sizeof(hdr))
return FALSE;
return TRUE;
}
static bfd_boolean
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_bwrite (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_get_section_contents_in_window \
_bfd_generic_get_section_contents_in_window
#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_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. */
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_generic_mkarchive,
_bfd_bool_bfd_false_error,
},
{ /* bfd_write_contents */
_bfd_bool_bfd_false_error,
msdos_write_object_contents,
_bfd_write_archive_contents,
_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
};
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