summaryrefslogtreecommitdiff
path: root/outcoff.c
blob: 21b9bac405973b2b60862483487a09b972cc07f1 (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
423
424
425
426
427
428
429
430
431
432
433
434
435
436
437
438
439
440
441
442
443
444
445
446
447
448
449
450
451
452
453
454
455
456
457
458
459
460
461
462
463
464
465
466
467
468
469
470
471
472
473
474
475
476
477
478
479
480
481
482
483
484
485
486
487
488
489
490
491
492
493
494
495
496
497
498
499
500
501
502
503
504
505
506
507
508
509
510
511
512
513
514
515
516
517
518
519
520
521
522
523
524
525
526
527
528
529
530
531
532
533
534
535
536
537
538
539
540
541
542
543
544
545
546
547
548
549
550
551
552
553
554
555
556
557
558
559
560
561
562
563
564
565
566
567
568
569
570
571
572
573
574
575
576
577
578
579
580
581
582
583
584
585
586
587
588
589
590
591
592
593
594
595
596
597
598
599
600
601
602
603
604
605
606
607
608
609
610
611
612
613
614
615
616
617
618
619
620
621
622
623
624
625
626
627
628
629
630
631
632
633
634
635
636
637
638
639
640
641
642
643
644
645
646
647
648
649
650
651
652
653
654
655
656
657
658
659
660
661
662
663
664
665
666
667
668
669
670
671
672
673
674
675
676
677
678
679
680
681
682
683
684
685
686
687
688
689
690
691
692
693
694
695
696
/* outcoff.c	output routines for the Netwide Assembler to produce
 *		COFF object files (for DJGPP and Win32)
 *
 * The Netwide Assembler is copyright (C) 1996 Simon Tatham and
 * Julian Hall. All rights reserved. The software is
 * redistributable under the licence given in the file "Licence"
 * distributed in the NASM archive.
 */

#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <ctype.h>
#include <time.h>

#include "nasm.h"
#include "nasmlib.h"
#include "outform.h"

#if defined(OF_COFF) || defined(OF_WIN32)

/*
 * Notes on COFF:
 *
 * (0) When I say `standard COFF' below, I mean `COFF as output and
 * used by DJGPP'. I assume DJGPP gets it right.
 *
 * (1) Win32 appears to interpret the term `relative relocation'
 * differently from standard COFF. Standard COFF understands a
 * relative relocation to mean that during relocation you add the
 * address of the symbol you're referencing, and subtract the base
 * address of the section you're in. Win32 COFF, by contrast, seems
 * to add the address of the symbol and then subtract the address
 * of THE BYTE AFTER THE RELOCATED DWORD. Hence the two formats are
 * subtly incompatible.
 *
 * (2) Win32 doesn't bother putting any flags in the header flags
 * field (at offset 0x12 into the file).
 *
 * (3) Win32 puts some weird flags into the section header table.
 * It uses flags 0x80000000 (writable), 0x40000000 (readable) and
 * 0x20000000 (executable) in the expected combinations, which
 * standard COFF doesn't seem to bother with, but it also does
 * something else strange: it also flags code sections as
 * 0x00500000 and data/bss as 0x00300000. Even Microsoft's
 * documentation doesn't explain what these things mean. I just go
 * ahead and use them anyway - it seems to work.
 *
 * (4) Both standard COFF and Win32 COFF seem to use the DWORD
 * field directly after the section name in the section header
 * table for something strange: they store what the address of the
 * section start point _would_ be, if you laid all the sections end
 * to end starting at zero. Dunno why. Microsoft's documentation
 * lists this field as "Virtual Size of Section", which doesn't
 * seem to fit at all. In fact, Win32 even includes non-linked
 * sections such as .drectve in this calculation. Not that I can be
 * bothered with those things anyway.
 *
 * (5) Standard COFF does something very strange to common
 * variables: the relocation point for a common variable is as far
 * _before_ the variable as its size stretches out _after_ it. So
 * we must fix up common variable references. Win32 seems to be
 * sensible on this one.
 */

/* Flag which version of COFF we are currently outputting. */
static int win32;

struct Reloc {
    struct Reloc *next;
    long address;		       /* relative to _start_ of section */
    long symbol;		       /* symbol number */
    enum {
	SECT_SYMBOLS,
	ABS_SYMBOL,
	REAL_SYMBOLS
    } symbase;			       /* relocation for symbol number :) */
    int relative;		       /* TRUE or FALSE */
};

struct Symbol {
    char name[9];
    long strpos;		       /* string table position of name */
    int section;		       /* section number where it's defined
					* - in COFF codes, not NASM codes */
    int is_global;		       /* is it a global symbol or not? */
    long value;			       /* address, or COMMON variable size */
};

static FILE *coffp;
static efunc error;
static char coff_infile[FILENAME_MAX];

struct Section {
    struct SAA *data;
    unsigned long len;
    int nrelocs;
    long index;
    struct Reloc *head, **tail;
    unsigned long flags;	       /* section flags */
    char name[9];
    long pos, relpos;
};

#define TEXT_FLAGS (win32 ? 0x60500020L : 0x20L)
#define DATA_FLAGS (win32 ? 0xC0300040L : 0x40L)
#define BSS_FLAGS (win32 ? 0xC0300080L : 0x80L)
#define INFO_FLAGS 0x00100A00L

#define SECT_DELTA 32
static struct Section **sects;
static int nsects, sectlen;

static struct SAA *syms;
static unsigned long nsyms;

static long def_seg;

static int initsym;

static struct RAA *bsym, *symval;

static struct SAA *strs;
static unsigned long strslen;

static void coff_gen_init(FILE *, efunc);
static void coff_sect_write (struct Section *, unsigned char *,
			     unsigned long);
static void coff_write (void);
static void coff_section_header (char *, long, long, long, long, int, long);
static void coff_write_relocs (struct Section *);
static void coff_write_symbols (void);

static void coff_win32_init(FILE *fp, efunc errfunc, ldfunc ldef) {
    win32 = TRUE;
    (void) ldef;		       /* placate optimisers */
    coff_gen_init(fp, errfunc);
}

static void coff_std_init(FILE *fp, efunc errfunc, ldfunc ldef) {
    win32 = FALSE;
    (void) ldef;		       /* placate optimisers */
    coff_gen_init(fp, errfunc);
}

static void coff_gen_init(FILE *fp, efunc errfunc) {
    coffp = fp;
    error = errfunc;
    sects = NULL;
    nsects = sectlen = 0;
    syms = saa_init((long)sizeof(struct Symbol));
    nsyms = 0;
    bsym = raa_init();
    symval = raa_init();
    strs = saa_init(1L);
    strslen = 0;
    def_seg = seg_alloc();
}

static void coff_cleanup(void) {
    struct Reloc *r;
    int i;

    coff_write();
    fclose (coffp);
    for (i=0; i<nsects; i++) {
	if (sects[i]->data)
	    saa_free (sects[i]->data);
	while (sects[i]->head) {
	    r = sects[i]->head;
	    sects[i]->head = sects[i]->head->next;
	    nasm_free (r);
	}
    }
    nasm_free (sects);
    saa_free (syms);
    raa_free (bsym);
    raa_free (symval);
    saa_free (strs);
}

static int coff_make_section (char *name, unsigned long flags) {
    struct Section *s;

    s = nasm_malloc (sizeof(*s));

    if (flags != BSS_FLAGS)
	s->data = saa_init (1L);
    else
	s->data = NULL;
    s->head = NULL;
    s->tail = &s->head;
    s->len = 0;
    s->nrelocs = 0;
    if (!strcmp(name, ".text"))
	s->index = def_seg;
    else
	s->index = seg_alloc();
    strncpy (s->name, name, 8);
    s->name[8] = '\0';
    s->flags = flags;

    if (nsects >= sectlen)
	sects = nasm_realloc (sects, (sectlen += SECT_DELTA)*sizeof(*sects));
    sects[nsects++] = s;

    return nsects-1;
}

static long coff_section_names (char *name, int pass, int *bits) {
    char *p;
    unsigned long flags;
    int i;

    /*
     * Default is 32 bits.
     */
    if (!name)
	*bits = 32;

    if (!name)
	return def_seg;

    p = name;
    while (*p && !isspace(*p)) p++;
    if (*p) *p++ = '\0';
    if (strlen(p) > 8) {
	error (ERR_WARNING, "COFF section names limited to 8 characters:"
	       " truncating");
	p[8] = '\0';
    }
    flags = 0;

    while (*p && isspace(*p)) p++;
    while (*p) {
	char *q = p;
	while (*p && !isspace(*p)) p++;
	if (*p) *p++ = '\0';
	while (*p && isspace(*p)) p++;
	
	if (!nasm_stricmp(q, "code") || !nasm_stricmp(q, "text")) {
	    flags = TEXT_FLAGS;
	} else if (!nasm_stricmp(q, "data")) {
	    flags = DATA_FLAGS;
	} else if (!nasm_stricmp(q, "bss")) {
	    flags = BSS_FLAGS;
	} else if (!nasm_stricmp(q, "info")) {
	    if (win32)
		flags = INFO_FLAGS;
	    else {
		flags = DATA_FLAGS;    /* gotta do something */
		error (ERR_NONFATAL, "standard COFF does not support"
		       " informational sections");
	    }
	}
    }

    for (i=0; i<nsects; i++)
	if (!strcmp(name, sects[i]->name))
	    break;
    if (i == nsects) {
	if (!strcmp(name, ".text") && !flags)
	    i = coff_make_section (name, TEXT_FLAGS);
	else if (!strcmp(name, ".data") && !flags)
	    i = coff_make_section (name, DATA_FLAGS);
	else if (!strcmp(name, ".bss") && !flags)
	    i = coff_make_section (name, BSS_FLAGS);
	else if (flags)
	    i = coff_make_section (name, flags);
	else
	    i = coff_make_section (name, TEXT_FLAGS);
	if (flags)
	    sects[i]->flags = flags;
    } else if (pass == 1) {
	if (flags)
	    error (ERR_WARNING, "section attributes ignored on"
		   " redeclaration of section `%s'", name);
    }

    return sects[i]->index;
}

static void coff_deflabel (char *name, long segment, long offset,
			   int is_global) {
    int pos = strslen+4;
    struct Symbol *sym;

    if (name[0] == '.' && name[1] == '.' && name[2] != '@') {
	error (ERR_NONFATAL, "unrecognised special symbol `%s'", name);
	return;
    }

    if (strlen(name) > 8) {
	saa_wbytes (strs, name, (long)(1+strlen(name)));
	strslen += 1+strlen(name);
    } else
	pos = -1;

    sym = saa_wstruct (syms);

    sym->strpos = pos;
    if (pos == -1)
	strcpy (sym->name, name);
    sym->is_global = !!is_global;
    if (segment == NO_SEG)
	sym->section = -1;      /* absolute symbol */
    else {
	int i;
	sym->section = 0;
	for (i=0; i<nsects; i++)
	    if (segment == sects[i]->index) {
		sym->section = i+1;
		break;
	    }
	if (!sym->section)
	    sym->is_global = TRUE;
    }
    if (is_global == 2)
	sym->value = offset;
    else
	sym->value = (sym->section == 0 ? 0 : offset);

    /*
     * define the references from external-symbol segment numbers
     * to these symbol records.
     */
    if (sym->section == 0)
	bsym = raa_write (bsym, segment, nsyms);

    if (segment != NO_SEG)
	symval = raa_write (symval, segment, sym->section ? 0 : sym->value);

    nsyms++;
}

static long coff_add_reloc (struct Section *sect, long segment,
			    int relative) {
    struct Reloc *r;

    r = *sect->tail = nasm_malloc(sizeof(struct Reloc));
    sect->tail = &r->next;
    r->next = NULL;

    r->address = sect->len;
    if (segment == NO_SEG)
	r->symbol = 0, r->symbase = ABS_SYMBOL;
    else {
	int i;
	r->symbase = REAL_SYMBOLS;
	for (i=0; i<nsects; i++)
	    if (segment == sects[i]->index) {
		r->symbol = i*2;
		r->symbase = SECT_SYMBOLS;
		break;
	    }
	if (r->symbase == REAL_SYMBOLS)
	    r->symbol = raa_read (bsym, segment);
    }
    r->relative = relative;

    sect->nrelocs++;

    /*
     * Return the fixup for standard COFF common variables.
     */
    if (r->symbase == REAL_SYMBOLS && !win32)
	return raa_read (symval, segment);
    else
	return 0;
}

static void coff_out (long segto, void *data, unsigned long type,
		      long segment, long wrt) {
    struct Section *s;
    long realbytes = type & OUT_SIZMASK;
    unsigned char mydata[4], *p;
    int i;

    if (wrt != NO_SEG) {
	wrt = NO_SEG;		       /* continue to do _something_ */
	error (ERR_NONFATAL, "WRT not supported by COFF output formats");
    }

    type &= OUT_TYPMASK;

    /*
     * handle absolute-assembly (structure definitions)
     */
    if (segto == NO_SEG) {
	if (type != OUT_RESERVE)
	    error (ERR_NONFATAL, "attempt to assemble code in [ABSOLUTE]"
		   " space");
	return;
    }

    s = NULL;
    for (i=0; i<nsects; i++)
	if (segto == sects[i]->index) {
	    s = sects[i];
	    break;
	}
    if (!s) {
	int tempint;		       /* ignored */
	if (segto != coff_section_names (".text", 2, &tempint))
	    error (ERR_PANIC, "strange segment conditions in COFF driver");
	else
	    s = sects[nsects-1];
    }

    if (!s->data && type != OUT_RESERVE) {
	error(ERR_WARNING, "attempt to initialise memory in"
	      " BSS section `%s': ignored", s->name);
	if (type == OUT_REL2ADR)
	    realbytes = 2;
	else if (type == OUT_REL4ADR)
	    realbytes = 4;
	s->len += realbytes;
	return;
    }

    if (type == OUT_RESERVE) {
	if (s->data) {
	    error(ERR_WARNING, "uninitialised space declared in"
		  " non-BSS section `%s': zeroing", s->name);
	    coff_sect_write (s, NULL, realbytes);
	} else
	    s->len += realbytes;
    } else if (type == OUT_RAWDATA) {
	if (segment != NO_SEG)
	    error(ERR_PANIC, "OUT_RAWDATA with other than NO_SEG");
	coff_sect_write (s, data, realbytes);
    } else if (type == OUT_ADDRESS) {
	if (realbytes == 2 && (segment != NO_SEG || wrt != NO_SEG))
	    error(ERR_NONFATAL, "COFF format does not support 16-bit"
		  " relocations");
	else {
	    long fix = 0;
	    if (segment != NO_SEG || wrt != NO_SEG) {
		if (wrt != NO_SEG) {
		    error(ERR_NONFATAL, "COFF format does not support"
			  " WRT types");
		} else if (segment % 2) {
		    error(ERR_NONFATAL, "COFF format does not support"
			  " segment base references");
		} else
		    fix = coff_add_reloc (s, segment, FALSE);
	    }
	    p = mydata;
	    WRITELONG (p, *(long *)data + fix);
	    coff_sect_write (s, mydata, realbytes);
	}
    } else if (type == OUT_REL2ADR) {
	error(ERR_NONFATAL, "COFF format does not support 16-bit"
	      " relocations");
    } else if (type == OUT_REL4ADR) {
	if (segment == segto)
	    error(ERR_PANIC, "intra-segment OUT_REL4ADR");
	else if (segment == NO_SEG && win32)
	    error(ERR_NONFATAL, "Win32 COFF does not correctly support"
		  " relative references to absolute addresses");
	else {
	    long fix = 0;
	    if (segment != NO_SEG && segment % 2) {
		error(ERR_NONFATAL, "COFF format does not support"
		      " segment base references");
	    } else
		fix = coff_add_reloc (s, segment, TRUE);
	    p = mydata;
	    if (win32) {
		WRITELONG (p, *(long*)data + 4 - realbytes + fix);
	    } else {
		WRITELONG (p, *(long*)data-(realbytes + s->len) + fix);
	    }
	    coff_sect_write (s, mydata, 4L);
	}
    }
}

static void coff_sect_write (struct Section *sect,
			     unsigned char *data, unsigned long len) {
    saa_wbytes (sect->data, data, len);
    sect->len += len;
}

static int coff_directives (char *directive, char *value, int pass) {
    return 0;
}

static void coff_write (void) {
    long pos, sympos, vsize;
    int i;

    /*
     * Work out how big the file will get. Calculate the start of
     * the `real' symbols at the same time.
     */
    pos = 0x14 + 0x28 * nsects;
    initsym = 3;		       /* two for the file, one absolute */
    for (i=0; i<nsects; i++) {
	if (sects[i]->data) {
	    sects[i]->pos = pos;
	    pos += sects[i]->len;
	    sects[i]->relpos = pos;
	    pos += 10 * sects[i]->nrelocs;
	} else
	    sects[i]->pos = sects[i]->relpos = 0L;
	initsym += 2;		       /* two for each section */
    }
    sympos = pos;

    /*
     * Output the COFF header.
     */
    fwriteshort (0x14C, coffp);	       /* MACHINE_i386 */
    fwriteshort (nsects, coffp);       /* number of sections */
    fwritelong (time(NULL), coffp);    /* time stamp */
    fwritelong (sympos, coffp);
    fwritelong (nsyms + initsym, coffp);
    fwriteshort (0, coffp);	       /* no optional header */
    /* Flags: 32-bit, no line numbers. Win32 doesn't even bother with them. */
    fwriteshort (win32 ? 0 : 0x104, coffp);

    /*
     * Output the section headers.
     */
    vsize = 0L;
    for (i=0; i<nsects; i++) {
	coff_section_header (sects[i]->name, vsize, sects[i]->len,
			     sects[i]->pos, sects[i]->relpos,
			     sects[i]->nrelocs, sects[i]->flags);
	vsize += sects[i]->len;
    }

    /*
     * Output the sections and their relocations.
     */
    for (i=0; i<nsects; i++)
	if (sects[i]->data) {
	    saa_fpwrite (sects[i]->data, coffp);
	    coff_write_relocs (sects[i]);
	}

    /*
     * Output the symbol and string tables.
     */
    coff_write_symbols();
    fwritelong (strslen+4, coffp);     /* length includes length count */
    saa_fpwrite (strs, coffp);
}

static void coff_section_header (char *name, long vsize,
				 long datalen, long datapos,
				 long relpos, int nrelocs, long flags) {
    char padname[8];

    memset (padname, 0, 8);
    strncpy (padname, name, 8);
    fwrite (padname, 8, 1, coffp);
    fwritelong (vsize, coffp);
    fwritelong (0L, coffp);	       /* RVA/offset - we ignore */
    fwritelong (datalen, coffp);
    fwritelong (datapos, coffp);
    fwritelong (relpos, coffp);
    fwritelong (0L, coffp);	       /* no line numbers - we don't do 'em */
    fwriteshort (nrelocs, coffp);
    fwriteshort (0, coffp);	       /* again, no line numbers */
    fwritelong (flags, coffp);
}

static void coff_write_relocs (struct Section *s) {
    struct Reloc *r;

    for (r = s->head; r; r = r->next) {
	fwritelong (r->address, coffp);
	fwritelong (r->symbol + (r->symbase == REAL_SYMBOLS ? initsym :
				 r->symbase == ABS_SYMBOL ? initsym-1 :
				 r->symbase == SECT_SYMBOLS ? 2 : 0), coffp);
	/*
	 * Strange: Microsoft's COFF documentation says 0x03 for an
	 * absolute relocation, but both Visual C++ and DJGPP agree
	 * that in fact it's 0x06. I'll use 0x06 until someone
	 * argues.
	 */
	fwriteshort (r->relative ? 0x14 : 0x06, coffp);
    }
}

static void coff_symbol (char *name, long strpos, long value,
			 int section, int type, int aux) {
    char padname[8];

    if (name) {
	memset (padname, 0, 8);
	strncpy (padname, name, 8);
	fwrite (padname, 8, 1, coffp);
    } else {
	fwritelong (0L, coffp);
	fwritelong (strpos, coffp);
    }
    fwritelong (value, coffp);
    fwriteshort (section, coffp);
    fwriteshort (0, coffp);
    fputc (type, coffp);
    fputc (aux, coffp);
}

static void coff_write_symbols (void) {
    char filename[18];
    int i;

    /*
     * The `.file' record, and the file name auxiliary record.
     */
    coff_symbol (".file", 0L, 0L, -2, 0x67, 1);
    memset (filename, 0, 18);
    strncpy (filename, coff_infile, 18);
    fwrite (filename, 18, 1, coffp);

    /*
     * The section records, with their auxiliaries.
     */
    memset (filename, 0, 18);	       /* useful zeroed buffer */

    for (i=0; i<nsects; i++) {
	coff_symbol (sects[i]->name, 0L, 0L, i+1, 3, 1);
	fwritelong (sects[i]->len, coffp);
	fwriteshort (sects[i]->nrelocs, coffp);
	fwrite (filename, 12, 1, coffp);
    }

    /*
     * The absolute symbol, for relative-to-absolute relocations.
     */
    coff_symbol (".absolut", 0L, 0L, -1, 3, 0);

    /*
     * The real symbols.
     */
    saa_rewind (syms);
    for (i=0; i<nsyms; i++) {
	struct Symbol *sym = saa_rstruct (syms);
	coff_symbol (sym->strpos == -1 ? sym->name : NULL,
		     sym->strpos, sym->value, sym->section,
		     sym->is_global ? 2 : 3, 0);
    }
}

static long coff_segbase (long segment) {
    return segment;
}

static void coff_std_filename (char *inname, char *outname, efunc error) {
    strcpy(coff_infile, inname);
    standard_extension (inname, outname, ".o", error);
}

static void coff_win32_filename (char *inname, char *outname, efunc error) {
    strcpy(coff_infile, inname);
    standard_extension (inname, outname, ".obj", error);
}

#endif /* defined(OF_COFF) || defined(OF_WIN32) */

#ifdef OF_COFF

struct ofmt of_coff = {
    "COFF (i386) object files (e.g. DJGPP for DOS)",
    "coff",
    coff_std_init,
    coff_out,
    coff_deflabel,
    coff_section_names,
    coff_segbase,
    coff_directives,
    coff_std_filename,
    coff_cleanup
};

#endif

#ifdef OF_WIN32

struct ofmt of_win32 = {
    "Microsoft Win32 (i386) object files",
    "win32",
    coff_win32_init,
    coff_out,
    coff_deflabel,
    coff_section_names,
    coff_segbase,
    coff_directives,
    coff_win32_filename,
    coff_cleanup
};

#endif