/* BFD back-end for MS-DOS executables. Copyright (C) 1990-2021 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 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, (file_ptr) 0, SEEK_SET) != 0 || (size = bfd_bread (&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_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, 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 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 };