ld.c

<B>Digital的Unix操作系统VAX 4.2源码</B>

		case 'x':
			xflag++;
			continue;
		case 'X':
			Xflag++;
			continue;
		case 'S':
			Sflag++; 
			continue;
		case 'r':
			rflag++;
			arflag++;
			continue;
		case 's':
			sflag++;
			xflag++;
			continue;
		case 'n':
			nflag++;
			Nflag = zflag = 0;
			continue;
		case 'N':
			Nflag++;
			nflag = zflag = 0;
			continue;
		case 'd':
			dflag++;
			continue;
		case 'i':
			printf("ld: -i ignored\n");
			continue;
		case 't':
			trace++;
			continue;
		case 'y':
			if (ap[i+1] == 0)
				error(1, "-y: symbol name missing");
			if (yflag == 0) {
				ytab = (char **)calloc(argc, sizeof (char **));
				if (ytab == 0)
					error(1, "ran out of memory (-y)");
			}
			ytab[yflag++] = &ap[i+1];
			goto next;
		case 'z':
			zflag++;
			Nflag = nflag = 0;
			continue;
		case 'Y':
			if (ap[++i] == '\0')
				ex_mode = sys_v; /* For pre-V2.4 compatibility */
			else if (strcmp("SYSTEM_FIVE", &ap[i]) == 0)
				ex_mode = sys_v;
			else if (strcmp("POSIX", &ap[i]) == 0)
				ex_mode = posix;
			else if (strcmp("BSD", &ap[i]) == 0)
				ex_mode = bsd;
			else
				error(-1, "warning: bad -Y argument");
			goto next;
		case 'L':
			goto next;
		default:
			filname = savestr("-x");	/* kludge */
			filname[1] = ap[i];		/* kludge */
			archdr.ar_name[0] = 0;		/* kludge */
			error(1, "bad flag");
		}
next:
		;
	}
	if (rflag == 0 && Nflag == 0 && nflag == 0)
		zflag++;
	endload(argc, argv);
	exit(0);
}

/*
 * Convert a ascii string which is a hex number.
 * Used by -T and -D options.
 */
htoi(p)
	register char *p;
{
	register int c, n;

	n = 0;
	while (c = *p++) {
		n <<= 4;
		if (isdigit(c))
			n += c - '0';
		else if (c >= 'a' && c <= 'f')
			n += 10 + (c - 'a');
		else if (c >= 'A' && c <= 'F')
			n += 10 + (c - 'A');
		else
			error(1, "badly formed hex number");
	}
	return (n);
}

void
delexit()
{
	struct stat stbuf;
	long size;
	char c = 0;

	bflush();
	unlink("l.out");
	/*
	 * We have to insure that the last block of the data segment
	 * is allocated a full pagesize block. If the underlying
	 * file system allocates frags that are smaller than pagesize,
	 * a full zero filled pagesize block needs to be allocated so 
	 * that when it is demand paged, the paged in block will be 
	 * appropriately filled with zeros.
	 */
	fstat(biofd, &stbuf);
	size = round(stbuf.st_size, pagesize);
	if (!rflag && size > stbuf.st_size) {
		lseek(biofd, size - 1, 0);
		if (write(biofd, &c, 1) != 1)
			delarg |= 4;
	}
	if (delarg==0 && (arflag==0 || dflag) && Aflag==0)	/*009*/
		(void) chmod(ofilename, ofilemode);
	exit (delarg);
}

endload(argc, argv)
	int argc; 
	char **argv;
{
	register int c, i; 
	long dnum;
	register char *ap, **p;

	clibseg = libseg;
	filname = 0;
	middle();
	setupout();
	p = argv+1;
	for (c=1; c<argc; c++) {
		ap = *p++;
		if (trace)
			printf("%s:\n", ap);
		if (*ap != '-') {
			load2arg(ap);
			continue;
		}
		for (i=1; ap[i]; i++) switch (ap[i]) {

		case 'D':
			dnum = htoi(*p);
			if (dorigin < dnum)
				while (dorigin < dnum)
					bputc(0, dout), dorigin++;
			/* fall into ... */
		case 'T':
		case 'u':
		case 'e':
		case 'o':
		case 'H':
			++c; 
			++p;
			/* fall into ... */
		default:
			continue;
		case 'A':
			funding = 1;
			load2arg(*p++);
			funding = 0;
			c++;
			continue;
		case 'Y':
		case 'y':
		case 'L':
			goto next;
		case 'l':
			ap[--i]='-'; 
			load2arg(&ap[i]);
			goto next;
		}
next:
		;
	}
	finishout();
}

/*
 * Scan file to find defined symbols.
 */
load1arg(cp)
	register char *cp;
{
	register struct ranlib *tp;
	off_t nloc;
	int kind;

	kind = getfile(cp);
	if (Mflag)
		printf("%s\n", filname);
	switch (kind) {

	/*
	 * Plain file.
	 */
	case 0:
		load1(0, 0L);
		break;

	/*
	 * Archive without table of contents.
	 * (Slowly) process each member.
	 */
	case 1:
		error(-1,
"warning: archive has no table of contents; add one using ranlib(1)");
		nloc = SARMAG;
		while (step(nloc))
			nloc += sizeof(archdr) +
			    round(atol(archdr.ar_size), sizeof (short));
		break;

	/*
	 * Archive with table of contents.
	 * Read the table of contents and its associated string table.
	 * Pass through the library resolving symbols until nothing changes
	 * for an entire pass (i.e. you can get away with backward references
	 * when there is a table of contents!)
	 */
	case 2:
		nloc = SARMAG + sizeof (archdr);
		dseek(&text, nloc, sizeof (tnum));
		mget((char *)&tnum, sizeof (tnum), &text);
		nloc += sizeof (tnum);
		tab = (struct ranlib *)malloc(tnum);
		if (tab == 0)
			error(1, "ran out of memory (toc)");
		dseek(&text, nloc, tnum);
		mget((char *)tab, tnum, &text);
		nloc += tnum;
		tnum /= sizeof (struct ranlib);
		dseek(&text, nloc, sizeof (ssiz));
		mget((char *)&ssiz, sizeof (ssiz), &text);
		nloc += sizeof (ssiz);
		tabstr = (char *)malloc(ssiz);
		if (tabstr == 0)
			error(1, "ran out of memory (tocstr)");
		dseek(&text, nloc, ssiz);
		mget((char *)tabstr, ssiz, &text);
		for (tp = &tab[tnum]; --tp >= tab;) {
			if (tp->ran_un.ran_strx < 0 ||
			    tp->ran_un.ran_strx >= ssiz)
				error(1, "mangled archive table of contents");
			tp->ran_un.ran_name = tabstr + tp->ran_un.ran_strx;
		}
		while (ldrand())
			continue;
		free((char *)tab);
		free(tabstr);
		nextlibp(-1);
		break;

	/*
	 * Table of contents is out of date, so search
	 * as a normal library (but skip the __.SYMDEF file).
	 */
	case 3:
		error(-1,
"warning: table of contents for archive is out of date; rerun ranlib(1)");
		nloc = SARMAG;
		do
			nloc += sizeof(archdr) +
			    round(atol(archdr.ar_size), sizeof(short));
		while (step(nloc));
		break;
	}
	close(infil);
}

/*
 * Advance to the next archive member, which
 * is at offset nloc in the archive.  If the member
 * is useful, record its location in the liblist structure
 * for use in pass2.  Mark the end of the archive in libilst with a -1.
 */
step(nloc)
	off_t nloc;
{

	dseek(&text, nloc, (long) sizeof archdr);
	if (text.size <= 0) {
		nextlibp(-1);
		return (0);
	}
	getarhdr();
	if (load1(1, nloc + (sizeof archdr)))
		nextlibp(nloc);
	return (1);
}

/*
 * Record the location of a useful archive member.
 * Recording -1 marks the end of files from an archive.
 * The liblist data structure is dynamically extended here.
 */
nextlibp(val)
	off_t val;
{

	if (clibseg->li_used == NROUT) {
		if (++clibseg == &libseg[NSEG])
			error(1, "too many files loaded from libraries");
		clibseg->li_first = (off_t *)malloc(NROUT * sizeof (off_t));
		if (clibseg->li_first == 0)
			error(1, "ran out of memory (nextlibp)");
	}
	clibseg->li_first[clibseg->li_used++] = val;
	if (val != -1 && Mflag)
		printf("\t%s\n", archdr.ar_name);
}

/*
 * One pass over an archive with a table of contents.
 * Remember the number of symbols currently defined,
 * then call step on members which look promising (i.e.
 * that define a symbol which is currently externally undefined).
 * Indicate to our caller whether this process netted any more symbols.
 */
ldrand()
{
	register struct nlist *sp, **hp;
	register struct ranlib *tp, *tplast;
	off_t loc;
	int nsymt = symx(nextsym);

	tplast = &tab[tnum-1];
	for (tp = tab; tp <= tplast; tp++) {
		if ((hp = slookup(tp->ran_un.ran_name)) == 0 || *hp == 0)
			continue;
		sp = *hp;
		if (sp->n_type != N_EXT+N_UNDF)
			continue;
		step(tp->ran_off);
		loc = tp->ran_off;
		while (tp < tplast && (tp+1)->ran_off == loc)
			tp++;
	}
	return (symx(nextsym) != nsymt);
}

/*
 * Examine a single file or archive member on pass 1.
 */
load1(libflg, loc)
	off_t loc;
{
	register struct nlist *sp;
	struct nlist *savnext;
	int ndef, nlocal, type, size, nsymt;
	register int i;
	off_t maxoff;
	struct stat stb;

	readhdr(loc);
	if (filhdr.a_syms == 0) {
		if (filhdr.a_text+filhdr.a_data == 0) {
/*	Even though there's nothing here, we still mkfsym the name.  011 */
			if (libflg == 0) /* 011 */
				ssize += sizeof cursym; /* 011 */
			return (0);
		}
		error(1, "no namelist");
	}
	if (libflg)
		maxoff = atol(archdr.ar_size);
	else {
		fstat(infil, &stb);
		maxoff = stb.st_size;
	}
	if (N_STROFF(filhdr) + sizeof (off_t) >= maxoff)
		error(1, "too small (old format .o?)");
	ctrel = tsize; cdrel += dsize; cbrel += bsize;
	ndef = 0;
	nlocal = sizeof cursym;
	savnext = nextsym;
	loc += N_SYMOFF(filhdr);
	dseek(&text, loc, filhdr.a_syms);
	dseek(&reloc, loc + filhdr.a_syms, sizeof(off_t));
	mget(&size, sizeof (size), &reloc);
	dseek(&reloc, loc + filhdr.a_syms+sizeof (off_t), size-sizeof (off_t));
	curstr = (char *)malloc(size);
	if (curstr == NULL)
		error(1, "no space for string table");
	mget(curstr+sizeof(off_t), size-sizeof(off_t), &reloc);
	while (text.size > 0) {
		mget((char *)&cursym, sizeof(struct nlist), &text);
		if (cursym.n_un.n_strx) {
			if (cursym.n_un.n_strx<sizeof(size) ||
			    cursym.n_un.n_strx>=size)
				error(1, "bad string table index (pass 1)");
			cursym.n_un.n_name = curstr + cursym.n_un.n_strx;
		}
		type = cursym.n_type;

		/* Count the number of source lines and source files
		 * found in the symbol table.  This information is used by
		 * dbx.  Unnamed blocks are counted as functions, but
		 * real procedures are counted from the loader namelist
		 * (N_TEXT+N_EXT, and N_TEXT symbols).
		 */
		if (type & N_STAB) {
		    switch (type) {
		        case N_LBRAC:
			case N_RBRAC:	/* unnamed blocks go in the functab */
			    nfun++;
			    break;

		        case N_SLINE:	/* source lines */
			    nsline++;
			    break;

			case N_SO:	/* source files with stab info */
			case N_SOL:	/* textual include files */
			    nsol++;
			    break;

			default:
			    break;
		    }
		}
		if ((type&N_EXT)==0) {
			if (Xflag==0 || type & N_STAB ||
				cursym.n_un.n_name[0]!='L'  )	/* SLR001 */
				nlocal += sizeof cursym;
			if (type == N_TEXT) nfun++;	/* vjh007 */
			continue;
		}
		symreloc();
		if (enter(lookup()))
			continue;
		if ((sp = lastsym)->n_type != N_EXT+N_UNDF)
			continue;
		if (cursym.n_type == N_EXT+N_UNDF) {
			if (cursym.n_value > sp->n_value)
				sp->n_value = cursym.n_value;
			continue;
		}
		if (sp->n_value != 0 && cursym.n_type == N_EXT+N_TEXT)
			continue;
		ndef++;
		sp->n_type = cursym.n_type;
		sp->n_value = cursym.n_value;
	}
	if (libflg==0 || ndef) {
		tsize += filhdr.a_text;
		dsize += round(filhdr.a_data, sizeof (long));
		bsize += round(filhdr.a_bss, sizeof (long));
		ssize += nlocal;
		trsize += filhdr.a_trsize;
		drsize += filhdr.a_drsize;
		if (funding)
			textbase = (*slookup("_end"))->n_value;
		nsymt = symx(nextsym);
		for (i = symx(savnext); i < nsymt; i++) {
			sp = xsym(i);
			sp->n_un.n_name = savestr(sp->n_un.n_name);
		}
		free(curstr);
		return (1);
	}
	/*
	 * No symbols defined by this library member.
	 * Rip out the hash table entries and reset the symbol table.
	 */
	symfree(savnext);
	free(curstr);
	return(0);
}

middle()
{
	register struct nlist *sp;
	long csize, t, corigin, ocsize;
	int nund, rnd;
	char s;
	register int i;
	int nsymt;

	torigin = 0; 
	dorigin = 0; 
	borigin = 0;

	p_etext = *slookup("_etext");
	p_edata = *slookup("_edata");
	p_end = *slookup("_end");
	/*
	 * If there are any undefined symbols, save the relocation bits.
	 */
	nsymt = symx(nextsym);
	if (rflag==0) {
		for (i = 0; i < nsymt; i++) {
			sp = xsym(i);
			if (sp->n_type==N_EXT+N_UNDF && sp->n_value==0 &&
			    sp!=p_end && sp!=p_edata && sp!=p_etext) {
				rflag++;
				dflag = 0;
				break;
			}
		}
	}
	if (rflag) 
		sflag = zflag = 0;
	/*
	 * Assign common locations.
	 */
	csize = 0;
	if (!Aflag)
		addsym = symseg[0].sy_first;
	tsize += hsize ;	/* Increase by size given with -H option */
	database = round(tsize+textbase,
	    (nflag||zflag? pagesize : sizeof (long)));

	/*
	 * If requested, start BSS on a 512 byte hardware page boundary
	 * (the 'pagesize' used in the rest of ld is the software page size).
	 * This code causes the data size to be padded out to a 512 byte
	 * interval.  BSS is started directly after data, and may still be
	 * included in data (not bss) since data (later in ld) is rounded
	 * up to a 'pagesize' boundary.
	 */
	if (Bflag)
		dsize = round(dsize, 512);

	if (dflag || rflag==0) {
		ldrsym(p_etext, tsize, N_EXT+N_TEXT);
		ldrsym(p_edata, dsize, N_EXT+N_DATA);
		ldrsym(p_end, bsize, N_EXT+N_BSS);
		for (i = symx(addsym); i < nsymt; i++) {
			sp = xsym(i);
			if ((s=sp->n_type)==N_EXT+N_UNDF &&
			    (t = sp->n_value)!=0) {
				if (t >= sizeof (double))
					rnd = sizeof (double);
				else if (t >= sizeof (long))
					rnd = sizeof (long);
				else
					rnd = sizeof (short);
				csize = round(csize, rnd);
				sp->n_value = csize;
				sp->n_type = N_EXT+N_COMM;
				ocsize = csize;	
				csize += t;
			}
			if (s&N_EXT && (s&N_TYPE)==N_UNDF && s&N_STAB) {
				sp->n_value = ocsize;
				sp->n_type = (s&N_STAB) | (N_EXT+N_COMM);
			}
		}
	}
	/*
	 * Now set symbols to their final value
	 */
	csize = round(csize, sizeof (long));
	torigin = textbase;
	dorigin = database;
	corigin = dorigin + dsize;
	borigin = corigin + csize;
	nund = 0;
	nsymt = symx(nextsym);
	for (i = symx(addsym); i<nsymt; i++) {