ed.c

这是一个同样来自贝尔实验室的和UNIX有着渊源的操作系统, 其简洁的设计和实现易于我们学习和理解

			c = *lp++;
			if(c == 0) {
				if(Bputrune(&iobuf, '\n') < 0)
					error(Q);
				break;
			}
			if(Bputrune(&iobuf, c) < 0)
				error(Q);
		}
	} while(a1 <= addr2);
	if(Bflush(&iobuf) < 0)
		error(Q);
}

int
append(int (*f)(void), int *a)
{
	int *a1, *a2, *rdot, nline, tl;

	nline = 0;
	dot = a;
	while((*f)() == 0) {
		if((dol-zero) >= nlall) {
			nlall += 512;
			a1 = realloc(zero, (nlall+5)*sizeof(int*));
			if(a1 == 0) {
				error("MEM?");
				rescue();
			}
			tl = a1 - zero;	/* relocate pointers */
			zero += tl;
			addr1 += tl;
			addr2 += tl;
			dol += tl;
			dot += tl;
		}
		tl = putline();
		nline++;
		a1 = ++dol;
		a2 = a1+1;
		rdot = ++dot;
		while(a1 > rdot)
			*--a2 = *--a1;
		*rdot = tl;
	}
	return nline;
}

void
add(int i)
{
	if(i && (given || dol > zero)) {
		addr1--;
		addr2--;
	}
	squeeze(0);
	newline();
	append(gettty, addr2);
}

void
browse(void)
{
	int forward, n;
	static bformat, bnum; /* 0 */

	forward = 1;
	peekc = getchr();
	if(peekc != '\n'){
		if(peekc == '-' || peekc == '+') {
			if(peekc == '-')
				forward = 0;
			getchr();
		}
		n = getnum();
		if(n > 0)
			bpagesize = n;
	}
	newline();
	if(pflag) {
		bformat = listf;
		bnum = listn;
	} else {
		listf = bformat;
		listn = bnum;
	}
	if(forward) {
		addr1 = addr2;
		addr2 += bpagesize;
		if(addr2 > dol)
			addr2 = dol;
	} else {
		addr1 = addr2-bpagesize;
		if(addr1 <= zero)
			addr1 = zero+1;
	}
	printcom();
}

void
callunix(void)
{
	int c, pid;
	Rune rune;
	char buf[512];
	char *p;

	setnoaddr();
	p = buf;
	while((c=getchr()) != EOF && c != '\n')
		if(p < &buf[sizeof(buf) - 6]) {
			rune = c;
			p += runetochar(p, &rune);
		}
	*p = 0;
	pid = fork();
	if(pid == 0) {
		execl("/bin/rc", "rc", "-c", buf, nil);
		exits("execl failed");
	}
	waiting = 1;
	while(waitpid() != pid)
		;
	waiting = 0;
	if(vflag)
		putst("!");
}

void
quit(void)
{
	if(vflag && fchange && dol!=zero) {
		fchange = 0;
		error(Q);
	}
	remove(tfname);
	exits(0);
}

void
onquit(int sig)
{
	USED(sig);
	quit();
}

void
rdelete(int *ad1, int *ad2)
{
	int *a1, *a2, *a3;

	a1 = ad1;
	a2 = ad2+1;
	a3 = dol;
	dol -= a2 - a1;
	do {
		*a1++ = *a2++;
	} while(a2 <= a3);
	a1 = ad1;
	if(a1 > dol)
		a1 = dol;
	dot = a1;
	fchange = 1;
}

void
gdelete(void)
{
	int *a1, *a2, *a3;

	a3 = dol;
	for(a1=zero; (*a1&01)==0; a1++)
		if(a1>=a3)
			return;
	for(a2=a1+1; a2<=a3;) {
		if(*a2 & 01) {
			a2++;
			dot = a1;
		} else
			*a1++ = *a2++;
	}
	dol = a1-1;
	if(dot > dol)
		dot = dol;
	fchange = 1;
}

Rune*
getline(int tl)
{
	Rune *lp, *bp;
	int nl;

	lp = linebuf;
	bp = getblock(tl, OREAD);
	nl = nleft;
	tl &= ~((BLKSIZE/2) - 1);
	while(*lp++ = *bp++) {
		nl -= sizeof(Rune);
		if(nl == 0) {
			bp = getblock(tl += BLKSIZE/2, OREAD);
			nl = nleft;
		}
	}
	return linebuf;
}

int
putline(void)
{
	Rune *lp, *bp;
	int nl, tl;

	fchange = 1;
	lp = linebuf;
	tl = tline;
	bp = getblock(tl, OWRITE);
	nl = nleft;
	tl &= ~((BLKSIZE/2)-1);
	while(*bp = *lp++) {
		if(*bp++ == '\n') {
			bp[-1] = 0;
			linebp = lp;
			break;
		}
		nl -= sizeof(Rune);
		if(nl == 0) {
			tl += BLKSIZE/2;
			bp = getblock(tl, OWRITE);
			nl = nleft;
		}
	}
	nl = tline;
	tline += ((lp-linebuf) + 03) & 077776;
	return nl;
}

void
blkio(int b, uchar *buf, long (*iofcn)(int, void *, long))
{
	seek(tfile, b*BLKSIZE, 0);
	if((*iofcn)(tfile, buf, BLKSIZE) != BLKSIZE) {
		error(T);
	}
}

Rune*
getblock(int atl, int iof)
{
	int bno, off;
	
	static uchar ibuff[BLKSIZE];
	static uchar obuff[BLKSIZE];

	bno = atl / (BLKSIZE/2);
	off = (atl<<1) & (BLKSIZE-1) & ~03;
	if(bno >= NBLK) {
		lastc = '\n';
		error(T);
	}
	nleft = BLKSIZE - off;
	if(bno == iblock) {
		ichanged |= iof;
		return (Rune*)(ibuff+off);
	}
	if(bno == oblock)
		return (Rune*)(obuff+off);
	if(iof == OREAD) {
		if(ichanged)
			blkio(iblock, ibuff, write);
		ichanged = 0;
		iblock = bno;
		blkio(bno, ibuff, read);
		return (Rune*)(ibuff+off);
	}
	if(oblock >= 0)
		blkio(oblock, obuff, write);
	oblock = bno;
	return (Rune*)(obuff+off);
}

void
init(void)
{
	int *markp;

	close(tfile);
	tline = 2;
	for(markp = names; markp < &names[26]; )
		*markp++ = 0;
	subnewa = 0;
	anymarks = 0;
	iblock = -1;
	oblock = -1;
	ichanged = 0;
	if((tfile = create(tfname, ORDWR, 0600)) < 0){
		error1(T);
		exits(0);
	}
	dot = dol = zero;
}

void
global(int k)
{
	Rune *gp, globuf[GBSIZE];
	int c, *a1;

	if(globp)
		error(Q);
	setwide();
	squeeze(dol > zero);
	c = getchr();
	if(c == '\n')
		error(Q);
	compile(c);
	gp = globuf;
	while((c=getchr()) != '\n') {
		if(c == EOF)
			error(Q);
		if(c == '\\') {
			c = getchr();
			if(c != '\n')
				*gp++ = '\\';
		}
		*gp++ = c;
		if(gp >= &globuf[GBSIZE-2])
			error(Q);
	}
	if(gp == globuf)
		*gp++ = 'p';
	*gp++ = '\n';
	*gp = 0;
	for(a1=zero; a1<=dol; a1++) {
		*a1 &= ~01;
		if(a1 >= addr1 && a1 <= addr2 && match(a1) == k)
			*a1 |= 01;
	}

	/*
	 * Special case: g/.../d (avoid n^2 algorithm)
	 */
	if(globuf[0] == 'd' && globuf[1] == '\n' && globuf[2] == 0) {
		gdelete();
		return;
	}
	for(a1=zero; a1<=dol; a1++) {
		if(*a1 & 01) {
			*a1 &= ~01;
			dot = a1;
			globp = globuf;
			commands();
			a1 = zero;
		}
	}
}

void
join(void)
{
	Rune *gp, *lp;
	int *a1;

	nonzero();
	gp = genbuf;
	for(a1=addr1; a1<=addr2; a1++) {
		lp = getline(*a1);
		while(*gp = *lp++)
			if(gp++ >= &genbuf[LBSIZE-2])
				error(Q);
	}
	lp = linebuf;
	gp = genbuf;
	while(*lp++ = *gp++)
		;
	*addr1 = putline();
	if(addr1 < addr2)
		rdelete(addr1+1, addr2);
	dot = addr1;
}

void
substitute(int inglob)
{
	int *mp, *a1, nl, gsubf, n;

	n = getnum();	/* OK even if n==0 */
	gsubf = compsub();
	for(a1 = addr1; a1 <= addr2; a1++) {
		if(match(a1)){
			int *ozero;
			int m = n;

			do {
				int span = loc2-loc1;

				if(--m <= 0) {
					dosub();
					if(!gsubf)
						break;
					if(span == 0) {	/* null RE match */
						if(*loc2 == 0)
							break;
						loc2++;
					}
				}
			} while(match(0));
			if(m <= 0) {
				inglob |= 01;
				subnewa = putline();
				*a1 &= ~01;
				if(anymarks) {
					for(mp=names; mp<&names[26]; mp++)
						if(*mp == *a1)
							*mp = subnewa;
				}
				subolda = *a1;
				*a1 = subnewa;
				ozero = zero;
				nl = append(getsub, a1);
				addr2 += nl;
				nl += zero-ozero;
				a1 += nl;
			}
		}
	}
	if(inglob == 0)
		error(Q);
}

int
compsub(void)
{
	int seof, c;
	Rune *p;

	seof = getchr();
	if(seof == '\n' || seof == ' ')
		error(Q);
	compile(seof);
	p = rhsbuf;
	for(;;) {
		c = getchr();
		if(c == '\\') {
			c = getchr();
			*p++ = ESCFLG;
			if(p >= &rhsbuf[LBSIZE/2])
				error(Q);
		} else
		if(c == '\n' && (!globp || !globp[0])) {
			peekc = c;
			pflag++;
			break;
		} else
		if(c == seof)
			break;
		*p++ = c;
		if(p >= &rhsbuf[LBSIZE/2])
			error(Q);
	}
	*p = 0;
	peekc = getchr();
	if(peekc == 'g') {
		peekc = 0;
		newline();
		return 1;
	}
	newline();
	return 0;
}

int
getsub(void)
{
	Rune *p1, *p2;

	p1 = linebuf;
	if((p2 = linebp) == 0)
		return EOF;
	while(*p1++ = *p2++)
		;
	linebp = 0;
	return 0;
}

void
dosub(void)
{
	Rune *lp, *sp, *rp;
	int c, n;

	lp = linebuf;
	sp = genbuf;
	rp = rhsbuf;
	while(lp < loc1)
		*sp++ = *lp++;
	while(c = *rp++) {
		if(c == '&'){
			sp = place(sp, loc1, loc2);
			continue;
		}
		if(c == ESCFLG && (c = *rp++) >= '1' && c < MAXSUB+'0') {
			n = c-'0';
			if(subexp[n].rsp && subexp[n].rep) {
				sp = place(sp, subexp[n].rsp, subexp[n].rep);
				continue;
			}
			error(Q);
		}
		*sp++ = c;
		if(sp >= &genbuf[LBSIZE])
			error(Q);
	}
	lp = loc2;
	loc2 = sp - genbuf + linebuf;
	while(*sp++ = *lp++)
		if(sp >= &genbuf[LBSIZE])
			error(Q);
	lp = linebuf;
	sp = genbuf;
	while(*lp++ = *sp++)
		;
}

Rune*
place(Rune *sp, Rune *l1, Rune *l2)
{

	while(l1 < l2) {
		*sp++ = *l1++;
		if(sp >= &genbuf[LBSIZE])
			error(Q);
	}
	return sp;
}

void
move(int cflag)
{
	int *adt, *ad1, *ad2;

	nonzero();
	if((adt = address())==0)	/* address() guarantees addr is in range */
		error(Q);
	newline();
	if(cflag) {
		int *ozero, delta;
		ad1 = dol;
		ozero = zero;
		append(getcopy, ad1++);
		ad2 = dol;
		delta = zero - ozero;
		ad1 += delta;
		adt += delta;
	} else {
		ad2 = addr2;
		for(ad1 = addr1; ad1 <= ad2;)
			*ad1++ &= ~01;
		ad1 = addr1;
	}
	ad2++;
	if(adt<ad1) {
		dot = adt + (ad2-ad1);
		if((++adt)==ad1)
			return;
		reverse(adt, ad1);
		reverse(ad1, ad2);
		reverse(adt, ad2);
	} else
	if(adt >= ad2) {
		dot = adt++;
		reverse(ad1, ad2);
		reverse(ad2, adt);
		reverse(ad1, adt);
	} else
		error(Q);
	fchange = 1;
}

void
reverse(int *a1, int *a2)
{
	int t;

	for(;;) {
		t = *--a2;
		if(a2 <= a1)
			return;
		*a2 = *a1;
		*a1++ = t;
	}
}

int
getcopy(void)
{
	if(addr1 > addr2)
		return EOF;
	getline(*addr1++);
	return 0;
}

void
compile(int eof)
{
	Rune c;
	char *ep;
	char expbuf[ESIZE];

	if((c = getchr()) == '\n') {
		peekc = c;
		c = eof;
	}
	if(c == eof) {
		if(!pattern)
			error(Q);
		return;
	}
	if(pattern) {
		free(pattern);
		pattern = 0;
	}
	ep = expbuf;
	do {
		if(c == '\\') {
			if(ep >= expbuf+sizeof(expbuf)) {
				error(Q);
				return;
			}
			ep += runetochar(ep, &c);
			if((c = getchr()) == '\n') {
				error(Q);
				return;
			}
		}
		if(ep >= expbuf+sizeof(expbuf)) {
			error(Q);
			return;
		}
		ep += runetochar(ep, &c);
	} while((c = getchr()) != eof && c != '\n');
	if(c == '\n')
		peekc = c;
	*ep = 0;
	pattern = regcomp(expbuf);
}

int
match(int *addr)
{
	if(!pattern)
		return 0;
	if(addr){
		if(addr == zero)
			return 0;
		subexp[0].rsp = getline(*addr);
	} else
		subexp[0].rsp = loc2;
	subexp[0].rep = 0;
	if(rregexec(pattern, linebuf, subexp, MAXSUB)) {
		loc1 = subexp[0].rsp;
		loc2 = subexp[0].rep;
		return 1;
	}
	loc1 = loc2 = 0;
	return 0;
	
}

void
putd(void)
{
	int r;

	r = count%10;
	count /= 10;
	if(count)
		putd();
	putchr(r + L'0');
}

void
putst(char *sp)
{
	Rune r;

	col = 0;
	for(;;) {
		sp += chartorune(&r, sp);
		if(r == 0)
			break;
		putchr(r);
	}
	putchr(L'\n');
}

void
putshst(Rune *sp)
{
	col = 0;
	while(*sp)
		putchr(*sp++);
	putchr(L'\n');
}

void
putchr(int ac)
{
	char *lp;
	int c;
	Rune rune;

	lp = linp;
	c = ac;
	if(listf) {
		if(c == '\n') {
			if(linp != line && linp[-1] == ' ') {
				*lp++ = '\\';
				*lp++ = 'n';
			}
		} else {
			if(col > (72-6-2)) {
				col = 8;
				*lp++ = '\\';
				*lp++ = '\n';
				*lp++ = '\t';
			}
			col++;
			if(c=='\b' || c=='\t' || c=='\\') {
				*lp++ = '\\';
				if(c == '\b')
					c = 'b';
				else
				if(c == '\t')
					c = 't';
				col++;
			} else
			if(c<' ' || c>='\177') {
				*lp++ = '\\';
				*lp++ = 'x';
				*lp++ =  hex[c>>12];
				*lp++ =  hex[c>>8&0xF];
				*lp++ =  hex[c>>4&0xF];
				c     =  hex[c&0xF];
				col += 5;
			}
		}
	}

	rune = c;
	lp += runetochar(lp, &rune);

	if(c == '\n' || lp >= &line[sizeof(line)-5]) {
		linp = line;
		write(oflag? 2: 1, line, lp-line);
		return;
	}
	linp = lp;
}

char*
mktemp(char *as)
{
	char *s;
	unsigned pid;
	int i;

	pid = getpid();
	s = as;
	while(*s++)
		;
	s--;
	while(*--s == 'X') {
		*s = pid % 10 + '0';
		pid /= 10;
	}
	s++;
	i = 'a';
	while(access(as, 0) != -1) {
		if(i == 'z')
			return "/";
		*s = i++;
	}
	return as;
}

void
regerror(char *s)
{
	USED(s);
	error(Q);
}