1 /* BFD back-end for Intel 386 COFF files (DJGPP variant with a stub).
2 Copyright (C) 1997-2016 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 All the functions below are called by the corresponding functions
27 from coffswap.h.
28 The only thing what they do is to adjust the information stored in
29 the COFF file which are offset into the file.
30 This is needed, because DJGPP uses a very special way to load and run
31 the coff image. It loads the image in memory and assumes then, that the
32 image had no stub by using the filepointers as pointers in the coff
33 image and NOT in the file.
34
35 To be compatible with any existing executables I have fixed this
36 here and NOT in the DJGPP startup code. */
37
38 #define TARGET_SYM i386_coff_go32stubbed_vec
39 #define TARGET_NAME "coff-go32-exe"
40 #define TARGET_UNDERSCORE '_'
41 #define COFF_GO32_EXE
42 #define COFF_LONG_SECTION_NAMES
43 #define COFF_SUPPORT_GNU_LINKONCE
44 #define COFF_LONG_FILENAMES
45
46 #define COFF_SECTION_ALIGNMENT_ENTRIES \
47 { COFF_SECTION_NAME_EXACT_MATCH (".data"), \
48 COFF_ALIGNMENT_FIELD_EMPTY, COFF_ALIGNMENT_FIELD_EMPTY, 4 }, \
49 { COFF_SECTION_NAME_EXACT_MATCH (".text"), \
50 COFF_ALIGNMENT_FIELD_EMPTY, COFF_ALIGNMENT_FIELD_EMPTY, 4 }, \
51 { COFF_SECTION_NAME_PARTIAL_MATCH (".debug"), \
52 COFF_ALIGNMENT_FIELD_EMPTY, COFF_ALIGNMENT_FIELD_EMPTY, 0 }, \
53 { COFF_SECTION_NAME_PARTIAL_MATCH (".gnu.linkonce.wi"), \
54 COFF_ALIGNMENT_FIELD_EMPTY, COFF_ALIGNMENT_FIELD_EMPTY, 0 }
55
56 #include "sysdep.h"
57 #include "bfd.h"
58
59 /* All that ..._PRE and ...POST functions are called from the corresponding
60 coff_swap... functions. The ...PRE functions are called at the beginning
61 of the function and the ...POST functions at the end of the swap routines. */
62
63 static void
64 adjust_filehdr_in_post (bfd *, void *, void *);
65 static void
66 adjust_filehdr_out_pre (bfd *, void *, void *);
67 static void
68 adjust_filehdr_out_post (bfd *, void *, void *);
69 static void
70 adjust_scnhdr_in_post (bfd *, void *, void *);
71 static void
72 adjust_scnhdr_out_pre (bfd *, void *, void *);
73 static void
74 adjust_scnhdr_out_post (bfd *, void *, void *);
75 static void
76 adjust_aux_in_post (bfd *, void *, int, int, int, int, void *);
77 static void
78 adjust_aux_out_pre (bfd *, void *, int, int, int, int, void *);
79 static void
80 adjust_aux_out_post (bfd *, void *, int, int, int, int, void *);
81 static void
82 create_go32_stub (bfd *);
83
84 #define COFF_ADJUST_FILEHDR_IN_POST adjust_filehdr_in_post
85 #define COFF_ADJUST_FILEHDR_OUT_PRE adjust_filehdr_out_pre
86 #define COFF_ADJUST_FILEHDR_OUT_POST adjust_filehdr_out_post
87
88 #define COFF_ADJUST_SCNHDR_IN_POST adjust_scnhdr_in_post
89 #define COFF_ADJUST_SCNHDR_OUT_PRE adjust_scnhdr_out_pre
90 #define COFF_ADJUST_SCNHDR_OUT_POST adjust_scnhdr_out_post
91
92 #define COFF_ADJUST_AUX_IN_POST adjust_aux_in_post
93 #define COFF_ADJUST_AUX_OUT_PRE adjust_aux_out_pre
94 #define COFF_ADJUST_AUX_OUT_POST adjust_aux_out_post
95
96 static const bfd_target *go32_check_format (bfd *);
97
98 #define COFF_CHECK_FORMAT go32_check_format
99
100 static bfd_boolean
101 go32_stubbed_coff_bfd_copy_private_bfd_data (bfd *, bfd *);
102
103 #define coff_bfd_copy_private_bfd_data go32_stubbed_coff_bfd_copy_private_bfd_data
104
105 #include "coff-i386.c"
106
107 /* This macro is used, because I cannot assume the endianness of the
108 host system. */
109 #define _H(index) (H_GET_16 (abfd, (header + index * 2)))
110
111 /* These bytes are a 2048-byte DOS executable, which loads the COFF
112 image into memory and then runs it. It is called 'stub'. */
113
114 static const unsigned char stub_bytes[GO32_STUBSIZE] =
115 {
116 #include "go32stub.h"
117 };
118
119 /*
120 I have not commented each swap function below, because the
121 technique is in any function the same. For the ...in function,
122 all the pointers are adjusted by adding GO32_STUBSIZE and for the
123 ...out function, it is subtracted first and after calling the
124 standard swap function it is reset to the old value. */
125
126 /* This macro is used for adjusting the filepointers, which
127 is done only, if the pointer is nonzero. */
128
129 #define ADJUST_VAL(val,diff) \
130 if (val != 0) val += diff
131
132 static void
adjust_filehdr_in_post(bfd * abfd ATTRIBUTE_UNUSED,void * src,void * dst)133 adjust_filehdr_in_post (bfd * abfd ATTRIBUTE_UNUSED,
134 void * src,
135 void * dst)
136 {
137 FILHDR *filehdr_src = (FILHDR *) src;
138 struct internal_filehdr *filehdr_dst = (struct internal_filehdr *) dst;
139
140 ADJUST_VAL (filehdr_dst->f_symptr, GO32_STUBSIZE);
141
142 /* Save now the stub to be used later. Put the stub data to FILEHDR_DST
143 first as coff_data (abfd) still does not exist. It may not even be ever
144 created as we are just checking the file format of ABFD. */
145 memcpy (filehdr_dst->go32stub, filehdr_src->stub, GO32_STUBSIZE);
146 filehdr_dst->f_flags |= F_GO32STUB;
147 }
148
149 static void
adjust_filehdr_out_pre(bfd * abfd,void * in,void * out)150 adjust_filehdr_out_pre (bfd * abfd, void * in, void * out)
151 {
152 struct internal_filehdr *filehdr_in = (struct internal_filehdr *) in;
153 FILHDR *filehdr_out = (FILHDR *) out;
154
155 /* Generate the stub. */
156 create_go32_stub (abfd);
157
158 /* Copy the stub to the file header. */
159 if (coff_data (abfd)->go32stub != NULL)
160 memcpy (filehdr_out->stub, coff_data (abfd)->go32stub, GO32_STUBSIZE);
161 else
162 /* Use the default. */
163 memcpy (filehdr_out->stub, stub_bytes, GO32_STUBSIZE);
164
165 ADJUST_VAL (filehdr_in->f_symptr, -GO32_STUBSIZE);
166 }
167
168 static void
adjust_filehdr_out_post(bfd * abfd ATTRIBUTE_UNUSED,void * in,void * out ATTRIBUTE_UNUSED)169 adjust_filehdr_out_post (bfd * abfd ATTRIBUTE_UNUSED,
170 void * in,
171 void * out ATTRIBUTE_UNUSED)
172 {
173 struct internal_filehdr *filehdr_in = (struct internal_filehdr *) in;
174 /* Undo the above change. */
175 ADJUST_VAL (filehdr_in->f_symptr, GO32_STUBSIZE);
176 }
177
178 static void
adjust_scnhdr_in_post(bfd * abfd ATTRIBUTE_UNUSED,void * ext ATTRIBUTE_UNUSED,void * in)179 adjust_scnhdr_in_post (bfd * abfd ATTRIBUTE_UNUSED,
180 void * ext ATTRIBUTE_UNUSED,
181 void * in)
182 {
183 struct internal_scnhdr *scnhdr_int = (struct internal_scnhdr *) in;
184
185 ADJUST_VAL (scnhdr_int->s_scnptr, GO32_STUBSIZE);
186 ADJUST_VAL (scnhdr_int->s_relptr, GO32_STUBSIZE);
187 ADJUST_VAL (scnhdr_int->s_lnnoptr, GO32_STUBSIZE);
188 }
189
190 static void
adjust_scnhdr_out_pre(bfd * abfd ATTRIBUTE_UNUSED,void * in,void * out ATTRIBUTE_UNUSED)191 adjust_scnhdr_out_pre (bfd * abfd ATTRIBUTE_UNUSED,
192 void * in,
193 void * out ATTRIBUTE_UNUSED)
194 {
195 struct internal_scnhdr *scnhdr_int = (struct internal_scnhdr *) in;
196
197 ADJUST_VAL (scnhdr_int->s_scnptr, -GO32_STUBSIZE);
198 ADJUST_VAL (scnhdr_int->s_relptr, -GO32_STUBSIZE);
199 ADJUST_VAL (scnhdr_int->s_lnnoptr, -GO32_STUBSIZE);
200 }
201
202 static void
adjust_scnhdr_out_post(bfd * abfd ATTRIBUTE_UNUSED,void * in,void * out ATTRIBUTE_UNUSED)203 adjust_scnhdr_out_post (bfd * abfd ATTRIBUTE_UNUSED,
204 void * in,
205 void * out ATTRIBUTE_UNUSED)
206 {
207 struct internal_scnhdr *scnhdr_int = (struct internal_scnhdr *) in;
208
209 ADJUST_VAL (scnhdr_int->s_scnptr, GO32_STUBSIZE);
210 ADJUST_VAL (scnhdr_int->s_relptr, GO32_STUBSIZE);
211 ADJUST_VAL (scnhdr_int->s_lnnoptr, GO32_STUBSIZE);
212 }
213
214 static void
adjust_aux_in_post(bfd * abfd ATTRIBUTE_UNUSED,void * ext1 ATTRIBUTE_UNUSED,int type,int in_class,int indx ATTRIBUTE_UNUSED,int numaux ATTRIBUTE_UNUSED,void * in1)215 adjust_aux_in_post (bfd * abfd ATTRIBUTE_UNUSED,
216 void * ext1 ATTRIBUTE_UNUSED,
217 int type,
218 int in_class,
219 int indx ATTRIBUTE_UNUSED,
220 int numaux ATTRIBUTE_UNUSED,
221 void * in1)
222 {
223 union internal_auxent *in = (union internal_auxent *) in1;
224
225 if (in_class == C_BLOCK || in_class == C_FCN || ISFCN (type)
226 || ISTAG (in_class))
227 {
228 ADJUST_VAL (in->x_sym.x_fcnary.x_fcn.x_lnnoptr, GO32_STUBSIZE);
229 }
230 }
231
232 static void
adjust_aux_out_pre(bfd * abfd ATTRIBUTE_UNUSED,void * inp,int type,int in_class,int indx ATTRIBUTE_UNUSED,int numaux ATTRIBUTE_UNUSED,void * extp ATTRIBUTE_UNUSED)233 adjust_aux_out_pre (bfd *abfd ATTRIBUTE_UNUSED,
234 void * inp,
235 int type,
236 int in_class,
237 int indx ATTRIBUTE_UNUSED,
238 int numaux ATTRIBUTE_UNUSED,
239 void * extp ATTRIBUTE_UNUSED)
240 {
241 union internal_auxent *in = (union internal_auxent *) inp;
242
243 if (in_class == C_BLOCK || in_class == C_FCN || ISFCN (type)
244 || ISTAG (in_class))
245 {
246 ADJUST_VAL (in->x_sym.x_fcnary.x_fcn.x_lnnoptr, -GO32_STUBSIZE);
247 }
248 }
249
250 static void
adjust_aux_out_post(bfd * abfd ATTRIBUTE_UNUSED,void * inp,int type,int in_class,int indx ATTRIBUTE_UNUSED,int numaux ATTRIBUTE_UNUSED,void * extp ATTRIBUTE_UNUSED)251 adjust_aux_out_post (bfd *abfd ATTRIBUTE_UNUSED,
252 void * inp,
253 int type,
254 int in_class,
255 int indx ATTRIBUTE_UNUSED,
256 int numaux ATTRIBUTE_UNUSED,
257 void * extp ATTRIBUTE_UNUSED)
258 {
259 union internal_auxent *in = (union internal_auxent *) inp;
260
261 if (in_class == C_BLOCK || in_class == C_FCN || ISFCN (type)
262 || ISTAG (in_class))
263 {
264 ADJUST_VAL (in->x_sym.x_fcnary.x_fcn.x_lnnoptr, GO32_STUBSIZE);
265 }
266 }
267
268 /* That's the function, which creates the stub. There are
269 different cases from where the stub is taken.
270 At first the environment variable $(GO32STUB) is checked and then
271 $(STUB) if it was not set.
272 If it exists and points to a valid stub the stub is taken from
273 that file. This file can be also a whole executable file, because
274 the stub is computed from the exe information at the start of that
275 file.
276
277 If there was any error, the standard stub (compiled in this file)
278 is taken. */
279
280 static void
create_go32_stub(bfd * abfd)281 create_go32_stub (bfd *abfd)
282 {
283 /* Do it only once. */
284 if (coff_data (abfd)->go32stub == NULL)
285 {
286 char *stub;
287 struct stat st;
288 int f;
289 unsigned char header[10];
290 char magic[8];
291 unsigned long coff_start;
292 long exe_start;
293
294 /* Check at first the environment variable $(GO32STUB). */
295 stub = getenv ("GO32STUB");
296 /* Now check the environment variable $(STUB). */
297 if (stub == NULL)
298 stub = getenv ("STUB");
299 if (stub == NULL)
300 goto stub_end;
301 if (stat (stub, &st) != 0)
302 goto stub_end;
303 #ifdef O_BINARY
304 f = open (stub, O_RDONLY | O_BINARY);
305 #else
306 f = open (stub, O_RDONLY);
307 #endif
308 if (f < 0)
309 goto stub_end;
310 if (read (f, &header, sizeof (header)) < 0)
311 {
312 close (f);
313 goto stub_end;
314 }
315 if (_H (0) != 0x5a4d) /* It is not an exe file. */
316 {
317 close (f);
318 goto stub_end;
319 }
320 /* Compute the size of the stub (it is every thing up
321 to the beginning of the coff image). */
322 coff_start = (long) _H (2) * 512L;
323 if (_H (1))
324 coff_start += (long) _H (1) - 512L;
325
326 /* Currently there is only a fixed stub size of 2048 bytes
327 supported. */
328 if (coff_start != 2048)
329 {
330 close (f);
331 goto stub_end;
332 }
333 exe_start = _H (4) * 16;
334 if ((long) lseek (f, exe_start, SEEK_SET) != exe_start)
335 {
336 close (f);
337 goto stub_end;
338 }
339 if (read (f, &magic, 8) != 8)
340 {
341 close (f);
342 goto stub_end;
343 }
344 if (! CONST_STRNEQ (magic, "go32stub"))
345 {
346 close (f);
347 goto stub_end;
348 }
349 /* Now we found a correct stub (hopefully). */
350 coff_data (abfd)->go32stub = bfd_alloc (abfd, (bfd_size_type) coff_start);
351 if (coff_data (abfd)->go32stub == NULL)
352 {
353 close (f);
354 return;
355 }
356 lseek (f, 0L, SEEK_SET);
357 if ((unsigned long) read (f, coff_data (abfd)->go32stub, coff_start)
358 != coff_start)
359 {
360 bfd_release (abfd, coff_data (abfd)->go32stub);
361 coff_data (abfd)->go32stub = NULL;
362 }
363 close (f);
364 }
365 stub_end:
366 /* There was something wrong above, so use now the standard builtin
367 stub. */
368 if (coff_data (abfd)->go32stub == NULL)
369 {
370 coff_data (abfd)->go32stub
371 = bfd_alloc (abfd, (bfd_size_type) GO32_STUBSIZE);
372 if (coff_data (abfd)->go32stub == NULL)
373 return;
374 memcpy (coff_data (abfd)->go32stub, stub_bytes, GO32_STUBSIZE);
375 }
376 }
377
378 /* If ibfd was a stubbed coff image, copy the stub from that bfd
379 to the new obfd. */
380
381 static bfd_boolean
go32_stubbed_coff_bfd_copy_private_bfd_data(bfd * ibfd,bfd * obfd)382 go32_stubbed_coff_bfd_copy_private_bfd_data (bfd *ibfd, bfd *obfd)
383 {
384 /* Check if both are the same targets. */
385 if (ibfd->xvec != obfd->xvec)
386 return TRUE;
387
388 /* Check if we have a source stub. */
389 if (coff_data (ibfd)->go32stub == NULL)
390 return TRUE;
391
392 /* As adjust_filehdr_out_pre may get called only after this function,
393 optionally allocate the output stub. */
394 if (coff_data (obfd)->go32stub == NULL)
395 coff_data (obfd)->go32stub = bfd_alloc (obfd,
396 (bfd_size_type) GO32_STUBSIZE);
397
398 /* Now copy the stub. */
399 if (coff_data (obfd)->go32stub != NULL)
400 memcpy (coff_data (obfd)->go32stub, coff_data (ibfd)->go32stub,
401 GO32_STUBSIZE);
402
403 return TRUE;
404 }
405
406 /* coff_object_p only checks 2 bytes F_MAGIC at GO32_STUBSIZE inside the file
407 which is too fragile. */
408
409 static const bfd_target *
go32_check_format(bfd * abfd)410 go32_check_format (bfd *abfd)
411 {
412 char mz[2];
413
414 if (bfd_bread (mz, 2, abfd) != 2 || mz[0] != 'M' || mz[1] != 'Z')
415 {
416 bfd_set_error (bfd_error_wrong_format);
417 return NULL;
418 }
419
420 if (bfd_seek (abfd, 0, SEEK_SET) != 0)
421 return NULL;
422
423 return coff_object_p (abfd);
424 }
425