| 1 | /* BFD back-end for MS-DOS executables. |
| 2 | Copyright (C) 1990-2019 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 | #include "coff/msdos.h" |
| 31 | |
| 32 | #define EXE_LOAD_HIGH 0x0000 |
| 33 | #define EXE_LOAD_LOW 0xffff |
| 34 | #define EXE_PAGE_SIZE 512 |
| 35 | |
| 36 | static bfd_boolean |
| 37 | msdos_mkobject (bfd *abfd) |
| 38 | { |
| 39 | bfd_default_set_arch_mach (abfd, bfd_arch_i386, bfd_mach_i386_i8086); |
| 40 | |
| 41 | return aout_32_mkobject (abfd); |
| 42 | } |
| 43 | |
| 44 | static const bfd_target * |
| 45 | msdos_object_p (bfd *abfd) |
| 46 | { |
| 47 | struct external_DOS_hdr hdr; |
| 48 | bfd_byte buffer[2]; |
| 49 | asection *section; |
| 50 | unsigned int size; |
| 51 | |
| 52 | if (bfd_seek (abfd, (file_ptr) 0, SEEK_SET) != 0 |
| 53 | || bfd_bread (&hdr, (bfd_size_type) sizeof (hdr), abfd) < DOS_HDR_SIZE) |
| 54 | { |
| 55 | if (bfd_get_error () != bfd_error_system_call) |
| 56 | bfd_set_error (bfd_error_wrong_format); |
| 57 | return NULL; |
| 58 | } |
| 59 | |
| 60 | if (H_GET_16 (abfd, hdr.e_magic) != IMAGE_DOS_SIGNATURE) |
| 61 | { |
| 62 | bfd_set_error (bfd_error_wrong_format); |
| 63 | return NULL; |
| 64 | } |
| 65 | |
| 66 | /* Check that this isn't actually a PE, NE, or LE file. If it is, the |
| 67 | e_lfanew field will be valid and point to a header beginning with one of |
| 68 | the relevant signatures. If not, e_lfanew might point to anything, so |
| 69 | don't bail if we can't read there. */ |
| 70 | if (H_GET_16 (abfd, hdr.e_cparhdr) < 4 |
| 71 | || bfd_seek (abfd, (file_ptr) H_GET_32 (abfd, hdr.e_lfanew), SEEK_SET) != 0 |
| 72 | || bfd_bread (buffer, (bfd_size_type) 2, abfd) != 2) |
| 73 | { |
| 74 | if (bfd_get_error () == bfd_error_system_call) |
| 75 | return NULL; |
| 76 | } |
| 77 | else |
| 78 | { |
| 79 | if (H_GET_16 (abfd, buffer) == IMAGE_NT_SIGNATURE |
| 80 | || H_GET_16 (abfd, buffer) == IMAGE_OS2_SIGNATURE |
| 81 | || H_GET_16 (abfd, buffer) == IMAGE_OS2_SIGNATURE_LE |
| 82 | || H_GET_16 (abfd, buffer) == IMAGE_OS2_SIGNATURE_LX) |
| 83 | { |
| 84 | bfd_set_error (bfd_error_wrong_format); |
| 85 | return NULL; |
| 86 | } |
| 87 | } |
| 88 | |
| 89 | if (!msdos_mkobject (abfd)) |
| 90 | return NULL; |
| 91 | |
| 92 | abfd->flags = EXEC_P; |
| 93 | abfd->start_address = H_GET_16 (abfd, hdr.e_ip); |
| 94 | |
| 95 | section = bfd_make_section (abfd, ".text"); |
| 96 | if (section == NULL) |
| 97 | return NULL; |
| 98 | |
| 99 | section->flags = (SEC_ALLOC | SEC_LOAD | SEC_CODE | SEC_HAS_CONTENTS); |
| 100 | section->filepos = H_GET_16 (abfd, hdr.e_cparhdr) * 16; |
| 101 | size = (H_GET_16 (abfd, hdr.e_cp) - 1) * EXE_PAGE_SIZE - section->filepos; |
| 102 | size += H_GET_16 (abfd, hdr.e_cblp); |
| 103 | |
| 104 | /* Check that the size is valid. */ |
| 105 | if (bfd_seek (abfd, (file_ptr) (section->filepos + size), SEEK_SET) != 0) |
| 106 | { |
| 107 | if (bfd_get_error () != bfd_error_system_call) |
| 108 | bfd_set_error (bfd_error_wrong_format); |
| 109 | return NULL; |
| 110 | } |
| 111 | |
| 112 | bfd_set_section_size (section, size); |
| 113 | section->alignment_power = 4; |
| 114 | |
| 115 | return abfd->xvec; |
| 116 | } |
| 117 | |
| 118 | static int |
| 119 | msdos_sizeof_headers (bfd *abfd ATTRIBUTE_UNUSED, |
| 120 | struct bfd_link_info *info ATTRIBUTE_UNUSED) |
| 121 | { |
| 122 | return 0; |
| 123 | } |
| 124 | |
| 125 | static bfd_boolean |
| 126 | msdos_write_object_contents (bfd *abfd) |
| 127 | { |
| 128 | static char hdr[EXE_PAGE_SIZE]; |
| 129 | file_ptr outfile_size = sizeof(hdr); |
| 130 | bfd_vma high_vma = 0; |
| 131 | asection *sec; |
| 132 | |
| 133 | /* Find the total size of the program on disk and in memory. */ |
| 134 | for (sec = abfd->sections; sec != (asection *) NULL; sec = sec->next) |
| 135 | { |
| 136 | if (sec->size == 0) |
| 137 | continue; |
| 138 | if (bfd_section_flags (sec) & SEC_ALLOC) |
| 139 | { |
| 140 | bfd_vma sec_vma = bfd_section_vma (sec) + sec->size; |
| 141 | if (sec_vma > high_vma) |
| 142 | high_vma = sec_vma; |
| 143 | } |
| 144 | if (bfd_section_flags (sec) & SEC_LOAD) |
| 145 | { |
| 146 | file_ptr sec_end = (sizeof (hdr) |
| 147 | + bfd_section_vma (sec) |
| 148 | + sec->size); |
| 149 | if (sec_end > outfile_size) |
| 150 | outfile_size = sec_end; |
| 151 | } |
| 152 | } |
| 153 | |
| 154 | /* Make sure the program isn't too big. */ |
| 155 | if (high_vma > (bfd_vma)0xffff) |
| 156 | { |
| 157 | bfd_set_error(bfd_error_file_too_big); |
| 158 | return FALSE; |
| 159 | } |
| 160 | |
| 161 | /* Constants. */ |
| 162 | H_PUT_16 (abfd, IMAGE_DOS_SIGNATURE, &hdr[0]); |
| 163 | H_PUT_16 (abfd, EXE_PAGE_SIZE / 16, &hdr[8]); |
| 164 | H_PUT_16 (abfd, EXE_LOAD_LOW, &hdr[12]); |
| 165 | H_PUT_16 (abfd, 0x3e, &hdr[24]); |
| 166 | H_PUT_16 (abfd, 0x0001, &hdr[28]); /* XXX??? */ |
| 167 | H_PUT_16 (abfd, 0x30fb, &hdr[30]); /* XXX??? */ |
| 168 | H_PUT_16 (abfd, 0x726a, &hdr[32]); /* XXX??? */ |
| 169 | |
| 170 | /* Bytes in last page (0 = full page). */ |
| 171 | H_PUT_16 (abfd, outfile_size & (EXE_PAGE_SIZE - 1), &hdr[2]); |
| 172 | |
| 173 | /* Number of pages. */ |
| 174 | H_PUT_16 (abfd, (outfile_size + EXE_PAGE_SIZE - 1) / EXE_PAGE_SIZE, &hdr[4]); |
| 175 | |
| 176 | /* Set the initial stack pointer to the end of the bss. |
| 177 | The program's crt0 code must relocate it to a real stack. */ |
| 178 | H_PUT_16 (abfd, high_vma, &hdr[16]); |
| 179 | |
| 180 | if (bfd_seek (abfd, (file_ptr) 0, SEEK_SET) != 0 |
| 181 | || bfd_bwrite (hdr, (bfd_size_type) sizeof(hdr), abfd) != sizeof(hdr)) |
| 182 | return FALSE; |
| 183 | |
| 184 | return TRUE; |
| 185 | } |
| 186 | |
| 187 | static bfd_boolean |
| 188 | msdos_set_section_contents (bfd *abfd, |
| 189 | sec_ptr section, |
| 190 | const void *location, |
| 191 | file_ptr offset, |
| 192 | bfd_size_type count) |
| 193 | { |
| 194 | |
| 195 | if (count == 0) |
| 196 | return TRUE; |
| 197 | |
| 198 | section->filepos = EXE_PAGE_SIZE + bfd_section_vma (section); |
| 199 | |
| 200 | if (bfd_section_flags (section) & SEC_LOAD) |
| 201 | { |
| 202 | if (bfd_seek (abfd, section->filepos + offset, SEEK_SET) != 0 |
| 203 | || bfd_bwrite (location, count, abfd) != count) |
| 204 | return FALSE; |
| 205 | } |
| 206 | |
| 207 | return TRUE; |
| 208 | } |
| 209 | |
| 210 | |
| 211 | |
| 212 | #define msdos_make_empty_symbol aout_32_make_empty_symbol |
| 213 | #define msdos_bfd_reloc_type_lookup aout_32_reloc_type_lookup |
| 214 | #define msdos_bfd_reloc_name_lookup aout_32_reloc_name_lookup |
| 215 | |
| 216 | #define msdos_close_and_cleanup _bfd_generic_close_and_cleanup |
| 217 | #define msdos_bfd_free_cached_info _bfd_generic_bfd_free_cached_info |
| 218 | #define msdos_new_section_hook _bfd_generic_new_section_hook |
| 219 | #define msdos_get_section_contents _bfd_generic_get_section_contents |
| 220 | #define msdos_get_section_contents_in_window \ |
| 221 | _bfd_generic_get_section_contents_in_window |
| 222 | #define msdos_bfd_get_relocated_section_contents \ |
| 223 | bfd_generic_get_relocated_section_contents |
| 224 | #define msdos_bfd_relax_section bfd_generic_relax_section |
| 225 | #define msdos_bfd_gc_sections bfd_generic_gc_sections |
| 226 | #define msdos_bfd_lookup_section_flags bfd_generic_lookup_section_flags |
| 227 | #define msdos_bfd_merge_sections bfd_generic_merge_sections |
| 228 | #define msdos_bfd_is_group_section bfd_generic_is_group_section |
| 229 | #define msdos_bfd_group_name bfd_generic_group_name |
| 230 | #define msdos_bfd_discard_group bfd_generic_discard_group |
| 231 | #define msdos_section_already_linked \ |
| 232 | _bfd_generic_section_already_linked |
| 233 | #define msdos_bfd_define_common_symbol bfd_generic_define_common_symbol |
| 234 | #define msdos_bfd_link_hide_symbol _bfd_generic_link_hide_symbol |
| 235 | #define msdos_bfd_define_start_stop bfd_generic_define_start_stop |
| 236 | #define msdos_bfd_link_hash_table_create _bfd_generic_link_hash_table_create |
| 237 | #define msdos_bfd_link_add_symbols _bfd_generic_link_add_symbols |
| 238 | #define msdos_bfd_link_just_syms _bfd_generic_link_just_syms |
| 239 | #define msdos_bfd_copy_link_hash_symbol_type \ |
| 240 | _bfd_generic_copy_link_hash_symbol_type |
| 241 | #define msdos_bfd_final_link _bfd_generic_final_link |
| 242 | #define msdos_bfd_link_split_section _bfd_generic_link_split_section |
| 243 | #define msdos_set_arch_mach _bfd_generic_set_arch_mach |
| 244 | #define msdos_bfd_link_check_relocs _bfd_generic_link_check_relocs |
| 245 | |
| 246 | #define msdos_get_symtab_upper_bound _bfd_nosymbols_get_symtab_upper_bound |
| 247 | #define msdos_canonicalize_symtab _bfd_nosymbols_canonicalize_symtab |
| 248 | #define msdos_print_symbol _bfd_nosymbols_print_symbol |
| 249 | #define msdos_get_symbol_info _bfd_nosymbols_get_symbol_info |
| 250 | #define msdos_get_symbol_version_string \ |
| 251 | _bfd_nosymbols_get_symbol_version_string |
| 252 | #define msdos_find_nearest_line _bfd_nosymbols_find_nearest_line |
| 253 | #define msdos_find_line _bfd_nosymbols_find_line |
| 254 | #define msdos_find_inliner_info _bfd_nosymbols_find_inliner_info |
| 255 | #define msdos_get_lineno _bfd_nosymbols_get_lineno |
| 256 | #define msdos_bfd_is_target_special_symbol _bfd_bool_bfd_asymbol_false |
| 257 | #define msdos_bfd_is_local_label_name _bfd_nosymbols_bfd_is_local_label_name |
| 258 | #define msdos_bfd_make_debug_symbol _bfd_nosymbols_bfd_make_debug_symbol |
| 259 | #define msdos_read_minisymbols _bfd_nosymbols_read_minisymbols |
| 260 | #define msdos_minisymbol_to_symbol _bfd_nosymbols_minisymbol_to_symbol |
| 261 | |
| 262 | #define msdos_canonicalize_reloc _bfd_norelocs_canonicalize_reloc |
| 263 | #define msdos_set_reloc _bfd_norelocs_set_reloc |
| 264 | #define msdos_get_reloc_upper_bound _bfd_norelocs_get_reloc_upper_bound |
| 265 | #define msdos_32_bfd_link_split_section _bfd_generic_link_split_section |
| 266 | |
| 267 | const bfd_target i386_msdos_vec = |
| 268 | { |
| 269 | "msdos", /* name */ |
| 270 | bfd_target_msdos_flavour, |
| 271 | BFD_ENDIAN_LITTLE, /* target byte order */ |
| 272 | BFD_ENDIAN_LITTLE, /* target headers byte order */ |
| 273 | (EXEC_P), /* object flags */ |
| 274 | (SEC_CODE | SEC_DATA | SEC_HAS_CONTENTS |
| 275 | | SEC_ALLOC | SEC_LOAD), /* section flags */ |
| 276 | 0, /* leading underscore */ |
| 277 | ' ', /* ar_pad_char */ |
| 278 | 16, /* ar_max_namelen */ |
| 279 | 0, /* match priority. */ |
| 280 | bfd_getl64, bfd_getl_signed_64, bfd_putl64, |
| 281 | bfd_getl32, bfd_getl_signed_32, bfd_putl32, |
| 282 | bfd_getl16, bfd_getl_signed_16, bfd_putl16, /* data */ |
| 283 | bfd_getl64, bfd_getl_signed_64, bfd_putl64, |
| 284 | bfd_getl32, bfd_getl_signed_32, bfd_putl32, |
| 285 | bfd_getl16, bfd_getl_signed_16, bfd_putl16, /* hdrs */ |
| 286 | |
| 287 | { |
| 288 | _bfd_dummy_target, |
| 289 | msdos_object_p, /* bfd_check_format */ |
| 290 | _bfd_dummy_target, |
| 291 | _bfd_dummy_target, |
| 292 | }, |
| 293 | { |
| 294 | _bfd_bool_bfd_false_error, |
| 295 | msdos_mkobject, |
| 296 | _bfd_generic_mkarchive, |
| 297 | _bfd_bool_bfd_false_error, |
| 298 | }, |
| 299 | { /* bfd_write_contents */ |
| 300 | _bfd_bool_bfd_false_error, |
| 301 | msdos_write_object_contents, |
| 302 | _bfd_write_archive_contents, |
| 303 | _bfd_bool_bfd_false_error, |
| 304 | }, |
| 305 | |
| 306 | BFD_JUMP_TABLE_GENERIC (msdos), |
| 307 | BFD_JUMP_TABLE_COPY (_bfd_generic), |
| 308 | BFD_JUMP_TABLE_CORE (_bfd_nocore), |
| 309 | BFD_JUMP_TABLE_ARCHIVE (_bfd_noarchive), |
| 310 | BFD_JUMP_TABLE_SYMBOLS (msdos), |
| 311 | BFD_JUMP_TABLE_RELOCS (msdos), |
| 312 | BFD_JUMP_TABLE_WRITE (msdos), |
| 313 | BFD_JUMP_TABLE_LINK (msdos), |
| 314 | BFD_JUMP_TABLE_DYNAMIC (_bfd_nodynamic), |
| 315 | |
| 316 | NULL, |
| 317 | |
| 318 | NULL |
| 319 | }; |
| 320 | |
| 321 | |