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nasm/output/outcoff.c

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/* 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 uses some extra flags into the section header table:
* it defines flags 0x80000000 (writable), 0x40000000 (readable)
* and 0x20000000 (executable), and uses them in the expected
* combinations. It also defines 0x00100000 through 0x00700000 for
* section alignments of 1 through 64 bytes.
*
* (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.
*
* (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 RDATA_FLAGS (win32 ? 0x40400040L : 0x40L)
#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, evalfunc eval)
{
win32 = TRUE;
(void) ldef; /* placate optimisers */
coff_gen_init(fp, errfunc);
}
static void coff_std_init(FILE *fp, efunc errfunc, ldfunc ldef, evalfunc eval)
{
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(int debuginfo)
{
struct Reloc *r;
int i;
(void) debuginfo;
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[i]);
}
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, align_and = ~0L, align_or = 0L;
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(name) > 8) {
error (ERR_WARNING, "COFF section names limited to 8 characters:"
" truncating");
name[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, "rdata")) {
if (win32)
flags = RDATA_FLAGS;
else {
flags = DATA_FLAGS; /* gotta do something */
error (ERR_NONFATAL, "standard COFF does not support"
" read-only data sections");
}
} 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");
}
} else if (!nasm_strnicmp(q,"align=",6)) {
if (!win32)
error (ERR_NONFATAL, "standard COFF does not support"
" section alignment specification");
else {
if (q[6+strspn(q+6,"0123456789")])
error(ERR_NONFATAL, "argument to `align' is not numeric");
else {
unsigned int align = atoi(q+6);
if (!align || ((align-1) & align))
error(ERR_NONFATAL, "argument to `align' is not a"
" power of two");
else if (align > 64)
error(ERR_NONFATAL, "Win32 cannot align sections"
" to better than 64-byte boundaries");
else {
align_and = ~0x00F00000L;
align_or = (align == 1 ? 0x00100000L :
align == 2 ? 0x00200000L :
align == 4 ? 0x00300000L :
align == 8 ? 0x00400000L :
align == 16 ? 0x00500000L :
align == 32 ? 0x00600000L : 0x00700000L);
}
}
}
}
}
for (i=0; i<nsects; i++)
if (!strcmp(name, sects[i]->name))
break;
if (i == nsects) {
if (!flags) {
if (!strcmp(name, ".data"))
flags = DATA_FLAGS;
else if (!strcmp(name, ".rdata"))
flags = RDATA_FLAGS;
else if (!strcmp(name, ".bss"))
flags = BSS_FLAGS;
else
flags = TEXT_FLAGS;
}
i = coff_make_section (name, flags);
if (flags)
sects[i]->flags = flags;
sects[i]->flags &= align_and;
sects[i]->flags |= align_or;
} 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, char *special)
{
int pos = strslen+4;
struct Symbol *sym;
if (special)
error (ERR_NONFATAL, "binary format does not support any"
" special symbol types");
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 != 4 && (segment != NO_SEG || wrt != NO_SEG))
error(ERR_NONFATAL, "COFF format does not support non-32-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];
unsigned long 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);
}
static const char *coff_stdmac[] = {
"%define __SECT__ [section .text]",
"%macro __NASM_CDecl__ 1",
"%endmacro",
NULL
};
static int coff_set_info(enum geninfo type, char **val)
{
return 0;
}
#endif /* defined(OF_COFF) || defined(OF_WIN32) */
#ifdef OF_COFF
struct ofmt of_coff = {
"COFF (i386) object files (e.g. DJGPP for DOS)",
"coff",
NULL,
null_debug_arr,
&null_debug_form,
coff_stdmac,
coff_std_init,
coff_set_info,
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",
NULL,
null_debug_arr,
&null_debug_form,
coff_stdmac,
coff_win32_init,
coff_set_info,
coff_out,
coff_deflabel,
coff_section_names,
coff_segbase,
coff_directives,
coff_win32_filename,
coff_cleanup
};
#endif
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