| 1 | /* BFD back-end for Intel 386 COFF files (DJGPP variant with a stub). |
| 2 | Copyright (C) 1997-2020 Free Software Foundation, Inc. |
| 3 | Written by Robert Hoehne. |
| 4 | |
| 5 | This file is part of BFD, the Binary File Descriptor library. |
| 6 | |
| 7 | This program is free software; you can redistribute it and/or modify |
| 8 | it under the terms of the GNU General Public License as published by |
| 9 | the Free Software Foundation; either version 3 of the License, or |
| 10 | (at your option) any later version. |
| 11 | |
| 12 | This program is distributed in the hope that it will be useful, |
| 13 | but WITHOUT ANY WARRANTY; without even the implied warranty of |
| 14 | MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the |
| 15 | GNU General Public License for more details. |
| 16 | |
| 17 | You should have received a copy of the GNU General Public License |
| 18 | along with this program; if not, write to the Free Software |
| 19 | Foundation, Inc., 51 Franklin Street - Fifth Floor, Boston, |
| 20 | MA 02110-1301, USA. */ |
| 21 | |
| 22 | /* This file handles now also stubbed coff images. The stub is a small |
| 23 | DOS executable program before the coff image to load it in memory |
| 24 | and execute it. This is needed, because DOS cannot run coff files. |
| 25 | |
| 26 | The COFF image is loaded in memory without the stub attached, so |
| 27 | all offsets are relative to the beginning of the image, not the |
| 28 | actual file. We handle this in bfd by setting bfd->origin to where |
| 29 | the COFF image starts. */ |
| 30 | |
| 31 | #define TARGET_SYM i386_coff_go32stubbed_vec |
| 32 | #define TARGET_NAME "coff-go32-exe" |
| 33 | #define TARGET_UNDERSCORE '_' |
| 34 | #define COFF_GO32_EXE |
| 35 | #define COFF_LONG_SECTION_NAMES |
| 36 | #define COFF_SUPPORT_GNU_LINKONCE |
| 37 | #define COFF_LONG_FILENAMES |
| 38 | |
| 39 | #define COFF_SECTION_ALIGNMENT_ENTRIES \ |
| 40 | { COFF_SECTION_NAME_EXACT_MATCH (".data"), \ |
| 41 | COFF_ALIGNMENT_FIELD_EMPTY, COFF_ALIGNMENT_FIELD_EMPTY, 4 }, \ |
| 42 | { COFF_SECTION_NAME_EXACT_MATCH (".text"), \ |
| 43 | COFF_ALIGNMENT_FIELD_EMPTY, COFF_ALIGNMENT_FIELD_EMPTY, 4 }, \ |
| 44 | { COFF_SECTION_NAME_PARTIAL_MATCH (".debug"), \ |
| 45 | COFF_ALIGNMENT_FIELD_EMPTY, COFF_ALIGNMENT_FIELD_EMPTY, 0 }, \ |
| 46 | { COFF_SECTION_NAME_PARTIAL_MATCH (".gnu.linkonce.wi"), \ |
| 47 | COFF_ALIGNMENT_FIELD_EMPTY, COFF_ALIGNMENT_FIELD_EMPTY, 0 } |
| 48 | |
| 49 | /* Section contains extended relocations. */ |
| 50 | #define IMAGE_SCN_LNK_NRELOC_OVFL (0x01000000) |
| 51 | |
| 52 | #include "sysdep.h" |
| 53 | #include "bfd.h" |
| 54 | #include "coff/msdos.h" |
| 55 | |
| 56 | static bfd_cleanup go32exe_check_format (bfd *); |
| 57 | static bfd_boolean go32exe_write_object_contents (bfd *); |
| 58 | static bfd_boolean go32exe_mkobject (bfd *); |
| 59 | static bfd_boolean go32exe_copy_private_bfd_data (bfd *, bfd *); |
| 60 | |
| 61 | /* Defined in coff-go32.c. */ |
| 62 | bfd_boolean _bfd_go32_mkobject (bfd *); |
| 63 | void _bfd_go32_swap_scnhdr_in (bfd *, void *, void *); |
| 64 | unsigned int _bfd_go32_swap_scnhdr_out (bfd *, void *, void *); |
| 65 | |
| 66 | #define COFF_CHECK_FORMAT go32exe_check_format |
| 67 | #define COFF_WRITE_CONTENTS go32exe_write_object_contents |
| 68 | #define coff_mkobject go32exe_mkobject |
| 69 | #define coff_bfd_copy_private_bfd_data go32exe_copy_private_bfd_data |
| 70 | #define coff_SWAP_scnhdr_in _bfd_go32_swap_scnhdr_in |
| 71 | #define coff_SWAP_scnhdr_out _bfd_go32_swap_scnhdr_out |
| 72 | |
| 73 | #include "coff-i386.c" |
| 74 | |
| 75 | /* This macro is used, because I cannot assume the endianness of the |
| 76 | host system. */ |
| 77 | #define _H(index) (H_GET_16 (abfd, (header + index * 2))) |
| 78 | |
| 79 | /* These bytes are a 2048-byte DOS executable, which loads the COFF |
| 80 | image into memory and then runs it. It is called 'stub'. */ |
| 81 | #define GO32EXE_DEFAULT_STUB_SIZE 2048 |
| 82 | static const unsigned char go32exe_default_stub[GO32EXE_DEFAULT_STUB_SIZE] = |
| 83 | { |
| 84 | #include "go32stub.h" |
| 85 | }; |
| 86 | |
| 87 | /* Temporary location for stub read from input file. */ |
| 88 | static char * go32exe_temp_stub = NULL; |
| 89 | static bfd_size_type go32exe_temp_stub_size = 0; |
| 90 | |
| 91 | /* That's the function, which creates the stub. There are |
| 92 | different cases from where the stub is taken. |
| 93 | At first the environment variable $(GO32STUB) is checked and then |
| 94 | $(STUB) if it was not set. |
| 95 | If it exists and points to a valid stub the stub is taken from |
| 96 | that file. This file can be also a whole executable file, because |
| 97 | the stub is computed from the exe information at the start of that |
| 98 | file. |
| 99 | |
| 100 | If there was any error, the standard stub (compiled in this file) |
| 101 | is taken. |
| 102 | |
| 103 | Ideally this function should exec '$(TARGET)-stubify' to generate |
| 104 | a stub, like gcc does. */ |
| 105 | |
| 106 | static void |
| 107 | go32exe_create_stub (bfd *abfd) |
| 108 | { |
| 109 | /* Do it only once. */ |
| 110 | if (coff_data (abfd)->stub == NULL) |
| 111 | { |
| 112 | char *stub; |
| 113 | struct stat st; |
| 114 | int f; |
| 115 | unsigned char header[10]; |
| 116 | char magic[8]; |
| 117 | unsigned long coff_start; |
| 118 | long exe_start; |
| 119 | |
| 120 | /* If we read a stub from an input file, use that one. */ |
| 121 | if (go32exe_temp_stub != NULL) |
| 122 | { |
| 123 | coff_data (abfd)->stub = bfd_alloc (abfd, |
| 124 | go32exe_temp_stub_size); |
| 125 | if (coff_data (abfd)->stub == NULL) |
| 126 | return; |
| 127 | memcpy (coff_data (abfd)->stub, go32exe_temp_stub, |
| 128 | go32exe_temp_stub_size); |
| 129 | coff_data (abfd)->stub_size = go32exe_temp_stub_size; |
| 130 | free (go32exe_temp_stub); |
| 131 | go32exe_temp_stub = NULL; |
| 132 | go32exe_temp_stub_size = 0; |
| 133 | return; |
| 134 | } |
| 135 | |
| 136 | /* Check at first the environment variable $(GO32STUB). */ |
| 137 | stub = getenv ("GO32STUB"); |
| 138 | /* Now check the environment variable $(STUB). */ |
| 139 | if (stub == NULL) |
| 140 | stub = getenv ("STUB"); |
| 141 | if (stub == NULL) |
| 142 | goto stub_end; |
| 143 | if (stat (stub, &st) != 0) |
| 144 | goto stub_end; |
| 145 | #ifdef O_BINARY |
| 146 | f = open (stub, O_RDONLY | O_BINARY); |
| 147 | #else |
| 148 | f = open (stub, O_RDONLY); |
| 149 | #endif |
| 150 | if (f < 0) |
| 151 | goto stub_end; |
| 152 | if (read (f, &header, sizeof (header)) < 0) |
| 153 | { |
| 154 | close (f); |
| 155 | goto stub_end; |
| 156 | } |
| 157 | if (_H (0) != 0x5a4d) /* It is not an exe file. */ |
| 158 | { |
| 159 | close (f); |
| 160 | goto stub_end; |
| 161 | } |
| 162 | /* Compute the size of the stub (it is every thing up |
| 163 | to the beginning of the coff image). */ |
| 164 | coff_start = (long) _H (2) * 512L; |
| 165 | if (_H (1)) |
| 166 | coff_start += (long) _H (1) - 512L; |
| 167 | |
| 168 | exe_start = _H (4) * 16; |
| 169 | if ((long) lseek (f, exe_start, SEEK_SET) != exe_start) |
| 170 | { |
| 171 | close (f); |
| 172 | goto stub_end; |
| 173 | } |
| 174 | if (read (f, &magic, 8) != 8) |
| 175 | { |
| 176 | close (f); |
| 177 | goto stub_end; |
| 178 | } |
| 179 | if (! CONST_STRNEQ (magic, "go32stub")) |
| 180 | { |
| 181 | close (f); |
| 182 | goto stub_end; |
| 183 | } |
| 184 | /* Now we found a correct stub (hopefully). */ |
| 185 | coff_data (abfd)->stub = bfd_alloc (abfd, (bfd_size_type) coff_start); |
| 186 | if (coff_data (abfd)->stub == NULL) |
| 187 | { |
| 188 | close (f); |
| 189 | return; |
| 190 | } |
| 191 | lseek (f, 0L, SEEK_SET); |
| 192 | if ((unsigned long) read (f, coff_data (abfd)->stub, coff_start) |
| 193 | != coff_start) |
| 194 | { |
| 195 | bfd_release (abfd, coff_data (abfd)->stub); |
| 196 | coff_data (abfd)->stub = NULL; |
| 197 | } |
| 198 | else |
| 199 | coff_data (abfd)->stub_size = coff_start; |
| 200 | close (f); |
| 201 | } |
| 202 | stub_end: |
| 203 | /* There was something wrong above, so use now the standard builtin |
| 204 | stub. */ |
| 205 | if (coff_data (abfd)->stub == NULL) |
| 206 | { |
| 207 | coff_data (abfd)->stub |
| 208 | = bfd_alloc (abfd, (bfd_size_type) GO32EXE_DEFAULT_STUB_SIZE); |
| 209 | if (coff_data (abfd)->stub == NULL) |
| 210 | return; |
| 211 | memcpy (coff_data (abfd)->stub, go32exe_default_stub, |
| 212 | GO32EXE_DEFAULT_STUB_SIZE); |
| 213 | coff_data (abfd)->stub_size = GO32EXE_DEFAULT_STUB_SIZE; |
| 214 | } |
| 215 | } |
| 216 | |
| 217 | /* If ibfd was a stubbed coff image, copy the stub from that bfd |
| 218 | to the new obfd. */ |
| 219 | |
| 220 | static bfd_boolean |
| 221 | go32exe_copy_private_bfd_data (bfd *ibfd, bfd *obfd) |
| 222 | { |
| 223 | /* Check if both are the same targets. */ |
| 224 | if (ibfd->xvec != obfd->xvec) |
| 225 | return TRUE; |
| 226 | |
| 227 | /* Make sure we have a source stub. */ |
| 228 | BFD_ASSERT (coff_data (ibfd)->stub != NULL); |
| 229 | |
| 230 | /* Reallocate the output stub if necessary. */ |
| 231 | if (coff_data (ibfd)->stub_size > coff_data (obfd)->stub_size) |
| 232 | coff_data (obfd)->stub = bfd_alloc (obfd, coff_data (ibfd)->stub_size); |
| 233 | if (coff_data (obfd)->stub == NULL) |
| 234 | return FALSE; |
| 235 | |
| 236 | /* Now copy the stub. */ |
| 237 | memcpy (coff_data (obfd)->stub, coff_data (ibfd)->stub, |
| 238 | coff_data (ibfd)->stub_size); |
| 239 | coff_data (obfd)->stub_size = coff_data (ibfd)->stub_size; |
| 240 | obfd->origin = coff_data (obfd)->stub_size; |
| 241 | |
| 242 | return TRUE; |
| 243 | } |
| 244 | |
| 245 | /* Cleanup function, returned from check_format hook. */ |
| 246 | |
| 247 | static void |
| 248 | go32exe_cleanup (bfd *abfd) |
| 249 | { |
| 250 | abfd->origin = 0; |
| 251 | |
| 252 | free (go32exe_temp_stub); |
| 253 | go32exe_temp_stub = NULL; |
| 254 | go32exe_temp_stub_size = 0; |
| 255 | } |
| 256 | |
| 257 | /* Check that there is a GO32 stub and read it to go32exe_temp_stub. |
| 258 | Then set abfd->origin so that the COFF image is read at the correct |
| 259 | file offset. */ |
| 260 | |
| 261 | static bfd_cleanup |
| 262 | go32exe_check_format (bfd *abfd) |
| 263 | { |
| 264 | struct external_DOS_hdr filehdr_dos; |
| 265 | uint16_t num_pages; |
| 266 | uint16_t last_page_size; |
| 267 | uint32_t header_end; |
| 268 | bfd_size_type stubsize; |
| 269 | |
| 270 | /* This format can not appear in an archive. */ |
| 271 | if (abfd->origin != 0) |
| 272 | { |
| 273 | bfd_set_error (bfd_error_wrong_format); |
| 274 | return NULL; |
| 275 | } |
| 276 | |
| 277 | bfd_set_error (bfd_error_system_call); |
| 278 | |
| 279 | /* Read in the stub file header, which is a DOS MZ executable. */ |
| 280 | if (bfd_bread (&filehdr_dos, DOS_HDR_SIZE, abfd) != DOS_HDR_SIZE) |
| 281 | goto fail; |
| 282 | |
| 283 | /* Make sure that this is an MZ executable. */ |
| 284 | if (H_GET_16 (abfd, filehdr_dos.e_magic) != IMAGE_DOS_SIGNATURE) |
| 285 | goto fail_format; |
| 286 | |
| 287 | /* Determine the size of the stub */ |
| 288 | num_pages = H_GET_16 (abfd, filehdr_dos.e_cp); |
| 289 | last_page_size = H_GET_16 (abfd, filehdr_dos.e_cblp); |
| 290 | stubsize = num_pages * 512; |
| 291 | if (last_page_size != 0) |
| 292 | stubsize += last_page_size - 512; |
| 293 | |
| 294 | /* Save now the stub to be used later. Put the stub data to a temporary |
| 295 | location first as tdata still does not exist. It may not even |
| 296 | be ever created if we are just checking the file format of ABFD. */ |
| 297 | bfd_seek (abfd, 0, SEEK_SET); |
| 298 | go32exe_temp_stub = bfd_malloc (stubsize); |
| 299 | if (go32exe_temp_stub == NULL) |
| 300 | goto fail; |
| 301 | if (bfd_bread (go32exe_temp_stub, stubsize, abfd) != stubsize) |
| 302 | goto fail; |
| 303 | go32exe_temp_stub_size = stubsize; |
| 304 | |
| 305 | /* Confirm that this is a go32stub. */ |
| 306 | header_end = H_GET_16 (abfd, filehdr_dos.e_cparhdr) * 16UL; |
| 307 | if (! CONST_STRNEQ (go32exe_temp_stub + header_end, "go32stub")) |
| 308 | goto fail_format; |
| 309 | |
| 310 | /* Set origin to where the COFF header starts and seek there. */ |
| 311 | abfd->origin = stubsize; |
| 312 | if (bfd_seek (abfd, 0, SEEK_SET) != 0) |
| 313 | goto fail; |
| 314 | |
| 315 | /* Call coff_object_p to read the COFF image. If this fails then the file |
| 316 | must be just a stub with no COFF data attached. */ |
| 317 | bfd_cleanup cleanup = coff_object_p (abfd); |
| 318 | if (cleanup == NULL) |
| 319 | goto fail; |
| 320 | BFD_ASSERT (cleanup == _bfd_no_cleanup); |
| 321 | |
| 322 | return go32exe_cleanup; |
| 323 | |
| 324 | fail_format: |
| 325 | bfd_set_error (bfd_error_wrong_format); |
| 326 | fail: |
| 327 | go32exe_cleanup (abfd); |
| 328 | return NULL; |
| 329 | } |
| 330 | |
| 331 | /* Write the stub to the output file, then call coff_write_object_contents. */ |
| 332 | |
| 333 | static bfd_boolean |
| 334 | go32exe_write_object_contents (bfd *abfd) |
| 335 | { |
| 336 | const bfd_size_type pos = bfd_tell (abfd); |
| 337 | const bfd_size_type stubsize = coff_data (abfd)->stub_size; |
| 338 | |
| 339 | BFD_ASSERT (stubsize != 0); |
| 340 | |
| 341 | bfd_set_error (bfd_error_system_call); |
| 342 | |
| 343 | /* Write the stub. */ |
| 344 | abfd->origin = 0; |
| 345 | if (bfd_seek (abfd, 0, SEEK_SET) != 0) |
| 346 | return FALSE; |
| 347 | if (bfd_bwrite (coff_data (abfd)->stub, stubsize, abfd) != stubsize) |
| 348 | return FALSE; |
| 349 | |
| 350 | /* Seek back to where we were. */ |
| 351 | abfd->origin = stubsize; |
| 352 | if (bfd_seek (abfd, pos, SEEK_SET) != 0) |
| 353 | return FALSE; |
| 354 | |
| 355 | return coff_write_object_contents (abfd); |
| 356 | } |
| 357 | |
| 358 | /* mkobject hook. Called directly through bfd_set_format or via |
| 359 | coff_mkobject_hook etc from bfd_check_format. */ |
| 360 | |
| 361 | static bfd_boolean |
| 362 | go32exe_mkobject (bfd *abfd) |
| 363 | { |
| 364 | /* Don't output to an archive. */ |
| 365 | if (abfd->my_archive != NULL) |
| 366 | return FALSE; |
| 367 | |
| 368 | if (!_bfd_go32_mkobject (abfd)) |
| 369 | return FALSE; |
| 370 | |
| 371 | go32exe_create_stub (abfd); |
| 372 | if (coff_data (abfd)->stub == NULL) |
| 373 | { |
| 374 | bfd_release (abfd, coff_data (abfd)); |
| 375 | return FALSE; |
| 376 | } |
| 377 | abfd->origin = coff_data (abfd)->stub_size; |
| 378 | |
| 379 | return TRUE; |
| 380 | } |