ld.c

<B>Digital的Unix操作系统VAX 4.2源码</B>

	cursym.n_value = torigin;
	symwrite(&cursym, sout);
}

getarhdr()
{
	register char *cp;

	mget((char *)&archdr, sizeof archdr, &text);
	for (cp=archdr.ar_name; cp<&archdr.ar_name[sizeof(archdr.ar_name)];)
		if (*cp++ == ' ') {
			cp[-1] = 0;
			return;
		}
}

mget(loc, n, sp)
register STREAM *sp;
register char *loc;
{
	register char *p;
	register int take;

top:
	if (n == 0)
		return;
	if (sp->size && sp->nibuf) {
		p = sp->ptr;
		take = sp->size;
		if (take > sp->nibuf)
			take = sp->nibuf;
		if (take > n)
			take = n;
		n -= take;
		sp->size -= take;
		sp->nibuf -= take;
		sp->pos += take;
		do
			*loc++ = *p++;
		while (--take > 0);
		sp->ptr = p;
		goto top;
	}
	if (n > p_blksize) {
		take = n - n % p_blksize;
		lseek(infil, (sp->bno+1)<<p_blkshift, 0);
		if (take > sp->size || read(infil, loc, take) != take)
			error(1, "premature EOF");
		loc += take;
		n -= take;
		sp->size -= take;
		sp->pos += take;
		dseek(sp, (sp->bno+1+(take>>p_blkshift))<<p_blkshift, -1);
		goto top;
	}
	*loc++ = get(sp);
	--n;
	goto top;
}

symwrite(sp, bp)
	struct nlist *sp;
	struct biobuf *bp;
{
	register int len;
	register char *str;

	str = sp->n_un.n_name;
	if (str) {
		sp->n_un.n_strx = offset;
		len = strlen(str) + 1;
		bwrite(str, len, strout);
		offset += len;
	}
	bwrite(sp, sizeof (*sp), bp);
	sp->n_un.n_name = str;
}

dseek(sp, loc, s)
register STREAM *sp;
long loc, s;
{
	register PAGE *p;
	register b, o;
	int n;

	b = loc>>p_blkshift;
	o = loc&p_blkmask;
	if (o&01)
		error(1, "loader error; odd offset");
	--sp->pno->nuser;
	if ((p = &page[0])->bno!=b && (p = &page[1])->bno!=b)
		if (p->nuser==0 || (p = &page[0])->nuser==0) {
			if (page[0].nuser==0 && page[1].nuser==0)
				if (page[0].bno < page[1].bno)
					p = &page[0];
			p->bno = b;
			lseek(infil, loc & ~(long)p_blkmask, 0);
			if ((n = read(infil, p->buff, p_blksize)) < 0)
				n = 0;
			p->nibuf = n;
		} else
			error(1, "botch: no pages");
	++p->nuser;
	sp->bno = b;
	sp->pno = p;
	if (s != -1) {sp->size = s; sp->pos = 0;}
	sp->ptr = (char *)(p->buff + o);
	if ((sp->nibuf = p->nibuf-o) <= 0)
		sp->size = 0;
}

char
get(asp)
STREAM *asp;
{
	register STREAM *sp;

	sp = asp;
	if ((sp->nibuf -= sizeof(char)) < 0) {
		dseek(sp, ((long)(sp->bno+1)<<p_blkshift), (long)-1);
		sp->nibuf -= sizeof(char);
	}
	if ((sp->size -= sizeof(char)) <= 0) {
		if (sp->size < 0)
			error(1, "premature EOF");
		++fpage.nuser;
		--sp->pno->nuser;
		sp->pno = (PAGE *) &fpage;
	}
	sp->pos += sizeof(char);
	return(*sp->ptr++);
}

getfile(acp)
char *acp;
{
	register int c;
	char arcmag[SARMAG+1];
	struct stat stb;

	archdr.ar_name[0] = '\0';
	filname = acp;
	if (filname[0] == '-' && filname[1] == 'l')
		infil = libopen(filname + 2, O_RDONLY);
	else
		infil = open(filname, O_RDONLY);
	if (infil < 0)
		error(1, "cannot open");
	fstat(infil, &stb);
	page[0].bno = page[1].bno = -1;
	page[0].nuser = page[1].nuser = 0;
	c = stb.st_blksize;
	if (c == 0 || (c & (c - 1)) != 0) {
		/* use default size if not a power of two */
		c = BLKSIZE;
	}
	if (p_blksize != c) {
		p_blksize = c;
		p_blkmask = c - 1;
		for (p_blkshift = 0; c > 1 ; p_blkshift++)
			c >>= 1;
		if (page[0].buff != NULL)
			free(page[0].buff);
		page[0].buff = (char *)malloc(p_blksize);
		if (page[0].buff == NULL)
			error(1, "ran out of memory (getfile)");
		if (page[1].buff != NULL)
			free(page[1].buff);
		page[1].buff = (char *)malloc(p_blksize);
		if (page[1].buff == NULL)
			error(1, "ran out of memory (getfile)");
	}
	text.pno = reloc.pno = (PAGE *) &fpage;
	fpage.nuser = 2;
	dseek(&text, 0L, SARMAG);
	if (text.size <= 0)
		error(1, "premature EOF");
	mget((char *)arcmag, SARMAG, &text);
	arcmag[SARMAG] = 0;
	if (strcmp(arcmag, ARMAG))
		return (0);
	dseek(&text, SARMAG, sizeof archdr);
	if (text.size <= 0)
		return (1);
	getarhdr();
	if (strncmp(archdr.ar_name, "__.SYMDEF", sizeof(archdr.ar_name)) != 0)
		return (1);
	return (stb.st_mtime > atol(archdr.ar_date) ? 3 : 2);
}

/*
 * Search for a library with given name
 * using the directory search array.
 */
libopen(name, oflags)
	char *name;
	int oflags;
{
	register char *p, *cp;
	register int i;
	static char buf[MAXPATHLEN+1];
	int fd = -1;

	if (*name == '\0')			/* backwards compat */
		name = "a";
	else if ((name[0] == 'g') && (name[1] == '\0'))
		gflag = 1;      /* -lg for dbx */

	for (i = 0; i < ndir && fd == -1; i++) {
		p = buf;
		for (cp = dirs[i]; *cp; *p++ = *cp++)
			;
		*p++ = '/';
		for (cp = "lib"; *cp; *p++ = *cp++)
			;
		for (cp = name; *cp; *p++ = *cp++)
			;
		cp = ".a";
		while (*p++ = *cp++)
			;
		fd = open(buf, oflags);
	}
	if (fd != -1)
		filname = buf;
	return (fd);
}

struct nlist **
lookup()
{
	register int sh; 
	register struct nlist **hp;
	register char *cp, *cp1;
	register struct symseg *gp;
	register int i;

	sh = 0;
	for (cp = cursym.n_un.n_name; *cp;)
		sh = (sh<<1) + *cp++;
	sh = (sh & 0x7fffffff) % HSIZE;
	for (gp = symseg; gp < &symseg[NSEG]; gp++) {
		if (gp->sy_first == 0) {
			gp->sy_first = (struct nlist *)
			    calloc(NSYM, sizeof (struct nlist));
			gp->sy_hfirst = (struct nlist **)
			    calloc(HSIZE, sizeof (struct nlist *));
			if (gp->sy_first == 0 || gp->sy_hfirst == 0)
				error(1, "ran out of space for symbol table");
			gp->sy_last = gp->sy_first + NSYM;
			gp->sy_hlast = gp->sy_hfirst + HSIZE;
		}
		if (gp > csymseg)
			csymseg = gp;
		hp = gp->sy_hfirst + sh;
		i = 1;
		do {
			if (*hp == 0) {
				if (gp->sy_used == NSYM)
					break;
				return (hp);
			}
			cp1 = (*hp)->n_un.n_name; 
			for (cp = cursym.n_un.n_name; *cp == *cp1++;)
				if (*cp++ == 0)
					return (hp);
			hp += i;
			i += 2;
			if (hp >= gp->sy_hlast)
				hp -= HSIZE;
		} while (i < HSIZE);
		if (i > HSIZE)
			error(1, "hash table botch");
	}
	error(1, "symbol table overflow");
	/*NOTREACHED*/
}

symfree(saved)
	struct nlist *saved;
{
	register struct symseg *gp;
	register struct nlist *sp;

	for (gp = csymseg; gp >= symseg; gp--, csymseg--) {
		sp = gp->sy_first + gp->sy_used;
		if (sp == saved) {
			nextsym = sp;
			return;
		}
		for (sp--; sp >= gp->sy_first; sp--) {
			gp->sy_hfirst[sp->n_hash] = 0;
			gp->sy_used--;
			if (sp == saved) {
				nextsym = sp;
				return;
			}
		}
	}
	if (saved == 0)
		return;
	error(1, "symfree botch");
}

struct nlist **
slookup(s)
	char *s;
{

	cursym.n_un.n_name = s;
	cursym.n_type = N_EXT+N_UNDF;
	cursym.n_value = 0;
	return (lookup());
}

enter(hp)
register struct nlist **hp;
{
	register struct nlist *sp;

	if (*hp==0) {
		if (hp < csymseg->sy_hfirst || hp >= csymseg->sy_hlast)
			error(1, "enter botch");
		*hp = lastsym = sp = csymseg->sy_first + csymseg->sy_used;
		csymseg->sy_used++;
		sp->n_un.n_name = cursym.n_un.n_name;
		sp->n_type = cursym.n_type;
		sp->n_hash = hp - csymseg->sy_hfirst;
		sp->n_value = cursym.n_value;
		nextsym = lastsym + 1;
		return(1);
	} else {
		lastsym = *hp;
		return(0);
	}
}

symx(sp)
	struct nlist *sp;
{
	register struct symseg *gp;

	if (sp == 0)
		return (0);
	for (gp = csymseg; gp >= symseg; gp--)
		/* <= is sloppy so nextsym will always work */
		if (sp >= gp->sy_first && sp <= gp->sy_last)
			return ((gp - symseg) * NSYM + sp - gp->sy_first);
	error(1, "symx botch");
	/*NOTREACHED*/
}

symreloc()
{
	if(funding) return;
	switch (cursym.n_type & 017) {

	case N_TEXT:
	case N_EXT+N_TEXT:
		cursym.n_value += ctrel;
		/* Count the number of functions in the symbol table.
		 * This information is supplied for dbx.
		 */
		nfun++;
		return;

	case N_DATA:
	case N_EXT+N_DATA:
		cursym.n_value += cdrel;
		return;

	case N_BSS:
	case N_EXT+N_BSS:
		cursym.n_value += cbrel;
		return;

	case N_EXT+N_UNDF:
		return;

	default:
		if (cursym.n_type&N_EXT)
			cursym.n_type = N_EXT+N_ABS;
		return;
	}
}

error(n, s)
char *s;
{

	if (errlev==0)
		printf("ld:");
	if (filname) {
		printf("%s", filname);
		if (n != -1 && archdr.ar_name[0])
			printf("(%s)", archdr.ar_name);
		printf(": ");
	}
	printf("%s\n", s);
	if (n == -1)
		return;
	if (n)
		delexit();
	errlev = 2;
}

readhdr(loc)
off_t loc;
{

	dseek(&text, loc, (long)sizeof(filhdr));
	mget((short *)&filhdr, sizeof(filhdr), &text);
	if (N_BADMAG(filhdr)) {
		if (filhdr.a_magic == OARMAG)
			error(1, "old archive");
		error(1, "bad magic number");
	}
	if (filhdr.a_text&01 || filhdr.a_data&01)
		error(1, "text/data size odd");
	if (filhdr.a_magic == NMAGIC || filhdr.a_magic == ZMAGIC) {
		cdrel = -round(filhdr.a_text, pagesize);
		cbrel = cdrel - filhdr.a_data;
	} else if (filhdr.a_magic == OMAGIC) {
		cdrel = -filhdr.a_text;
		cbrel = cdrel - filhdr.a_data;
	} else
		error(1, "bad format");
}

round(v, r)
	int v;
	u_long r;
{

	r--;
	v += r;
	v &= ~(long)r;
	return(v);
}

#define	NSAVETAB	8192
char	*savetab;
int	saveleft;

char *
savestr(cp)
	register char *cp;
{
	register int len;

	len = strlen(cp) + 1;
	if (len > saveleft) {
		saveleft = NSAVETAB;
		if (len > saveleft)
			saveleft = len;
		savetab = malloc(saveleft);
		if (savetab == 0)
			error(1, "ran out of memory (savestr)");
	}
	strncpy(savetab, cp, len);
	cp = savetab;
	savetab += len;
	saveleft -= len;
	return (cp);
}

bopen(bp, off, bufsize)
	register struct biobuf *bp;
{

	bp->b_ptr = bp->b_buf = malloc(bufsize);
	if (bp->b_ptr == (char *)0)
		error(1, "ran out of memory (bopen)");
	bp->b_bufsize = bufsize;
	bp->b_nleft = bufsize - (off % bufsize);
	bp->b_off = off;
	bp->b_link = biobufs;
	biobufs = bp;
}

int	bwrerror;

bwrite(p, cnt, bp)
	register char *p;
	register int cnt;
	register struct biobuf *bp;
{
	register int put;
	register char *to;

top:
	if (cnt == 0)
		return;
	if (bp->b_nleft) {
		put = bp->b_nleft;
		if (put > cnt)
			put = cnt;
		bp->b_nleft -= put;
		to = bp->b_ptr;
		bcopy(p, to, put);
		bp->b_ptr += put;
		p += put;
		cnt -= put;
		goto top;
	}
	if (cnt >= bp->b_bufsize) {
		if (bp->b_ptr != bp->b_buf)
			bflush1(bp);
		put = cnt - cnt % bp->b_bufsize;
		if (boffset != bp->b_off)
			lseek(biofd, bp->b_off, 0);
		if (write(biofd, p, put) != put) {
			bwrerror = 1;
			error(1, "output write error");
		}
		bp->b_off += put;
		boffset = bp->b_off;
		p += put;
		cnt -= put;
		goto top;
	}
	bflush1(bp);
	goto top;
}

bflush()
{
	register struct biobuf *bp;

	if (bwrerror)
		return;
	for (bp = biobufs; bp; bp = bp->b_link)
		bflush1(bp);
}

bflush1(bp)
	register struct biobuf *bp;
{
	register int cnt = bp->b_ptr - bp->b_buf;

	if (cnt == 0)
		return;
	if (boffset != bp->b_off)
		lseek(biofd, bp->b_off, 0);
	if (write(biofd, bp->b_buf, cnt) != cnt) {
		bwrerror = 1;
		error(1, "output write error");
	}
	bp->b_off += cnt;
	boffset = bp->b_off;
	bp->b_ptr = bp->b_buf;
	bp->b_nleft = bp->b_bufsize;
}

bflushc(bp, c)
	register struct biobuf *bp;
{

	bflush1(bp);
	bputc(c, bp);
}

bseek(bp, off)
	register struct biobuf *bp;
	register off_t off;
{
	bflush1(bp);
	
	bp->b_nleft = bp->b_bufsize - (off % bp->b_bufsize);
	bp->b_off = off;
}