xfid.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

		qunlock(&x->active);
		return;

	case Qconsctl:
		if(strncmp(x->data, "holdon", 6)==0){
			if(w->holding++ == 0)
				wsendctlmesg(w, Holdon, ZR, nil);
			break;
		}
		if(strncmp(x->data, "holdoff", 7)==0 && w->holding){
			if(--w->holding == FALSE)
				wsendctlmesg(w, Holdoff, ZR, nil);
			break;
		}
		if(strncmp(x->data, "rawon", 5)==0){
			if(w->holding){
				w->holding = FALSE;
				wsendctlmesg(w, Holdoff, ZR, nil);
			}
			if(w->rawing++ == 0)
				wsendctlmesg(w, Rawon, ZR, nil);
			break;
		}
		if(strncmp(x->data, "rawoff", 6)==0 && w->rawing){
			if(--w->rawing == 0)
				wsendctlmesg(w, Rawoff, ZR, nil);
			break;
		}
		filsysrespond(x->fs, x, &fc, "unknown control message");
		return;

	case Qcursor:
		if(cnt < 2*4+2*2*16)
			w->cursorp = nil;
		else{
			w->cursor.offset.x = BGLONG(x->data+0*4);
			w->cursor.offset.y = BGLONG(x->data+1*4);
			memmove(w->cursor.clr, x->data+2*4, 2*2*16);
			w->cursorp = &w->cursor;
		}
		wsetcursor(w, !sweeping);
		break;

	case Qlabel:
		if(off != 0){
			filsysrespond(x->fs, x, &fc, "non-zero offset writing label");
			return;
		}
		free(w->label);
		w->label = emalloc(cnt+1);
		memmove(w->label, x->data, cnt);
		w->label[cnt] = 0;
		break;

	case Qmouse:
		if(w!=input || Dx(w->screenr)<=0)
			break;
		if(x->data[0] != 'm'){
			filsysrespond(x->fs, x, &fc, Ebadmouse);
			return;
		}
		p = nil;
		pt.x = strtoul(x->data+1, &p, 0);
		if(p == nil){
			filsysrespond(x->fs, x, &fc, Eshort);
			return;
		}
		pt.y = strtoul(p, nil, 0);
		if(w==input && wpointto(mouse->xy)==w)
			wsendctlmesg(w, Movemouse, Rpt(pt, pt), nil);
		break;

	case Qsnarf:
		/* always append only */
		if(ntsnarf > MAXSNARF){	/* avoid thrashing when people cut huge text */
			filsysrespond(x->fs, x, &fc, Elong);
			return;
		}
		tsnarf = erealloc(tsnarf, ntsnarf+cnt+1);	/* room for NUL */
		memmove(tsnarf+ntsnarf, x->data, cnt);
		ntsnarf += cnt;
		snarfversion++;
		break;

	case Qwdir:
		if(cnt == 0)
			break;
		if(x->data[cnt-1] == '\n'){
			if(cnt == 1)
				break;
			x->data[cnt-1] = '\0';
		}
		/* assume data comes in a single write */
		/*
		  * Problem: programs like dossrv, ftp produce illegal UTF;
		  * we must cope by converting it first.
		  */
		snprint(buf, sizeof buf, "%.*s", cnt, x->data);
		if(buf[0] == '/'){
			free(w->dir);
			w->dir = estrdup(buf);
		}else{
			p = emalloc(strlen(w->dir) + 1 + strlen(buf) + 1);
			sprint(p, "%s/%s", w->dir, buf);
			free(w->dir);
			w->dir = cleanname(p);
		}
		break;

	case Qkbdin:
		keyboardsend(x->data, cnt);
		break;

	case Qwctl:
		if(writewctl(x, buf) < 0){
			filsysrespond(x->fs, x, &fc, buf);
			return;
		}
		flushimage(display, 1);
		break;

	default:
		fprint(2, buf, "unknown qid %d in write\n", qid);
		sprint(buf, "unknown qid in write");
		filsysrespond(x->fs, x, &fc, buf);
		return;
	}
	fc.count = cnt;
	filsysrespond(x->fs, x, &fc, nil);
}

int
readwindow(Image *i, char *t, Rectangle r, int offset, int n)
{
	int ww, y;

	offset -= 5*12;
	ww = bytesperline(r, screen->depth);
	r.min.y += offset/ww;
	if(r.min.y >= r.max.y)
		return 0;
	y = r.min.y + n/ww;
	if(y < r.max.y)
		r.max.y = y;
	if(r.max.y <= r.min.y)
		return 0;
	return unloadimage(i, r, (uchar*)t, n);
}

void
xfidread(Xfid *x)
{
	Fcall fc;
	int n, off, cnt, c;
	uint qid;
	char buf[128], *t;
	char cbuf[30];
	Window *w;
	Mouse ms;
	Rectangle r;
	Image *i;
	Channel *c1, *c2;	/* chan (tuple(char*, int)) */
	Consreadmesg crm;
	Mousereadmesg mrm;
	Consreadmesg cwrm;
	Stringpair pair;
	enum { CRdata, CRflush, NCR };
	enum { MRdata, MRflush, NMR };
	enum { WCRdata, WCRflush, NWCR };
	Alt alts[NCR+1];

	w = x->f->w;
	if(w->deleted){
		filsysrespond(x->fs, x, &fc, Edeleted);
		return;
	}
	qid = FILE(x->f->qid);
	off = x->offset;
	cnt = x->count;
	switch(qid){
	case Qcons:
		x->flushtag = x->tag;

		alts[CRdata].c = w->consread;
		alts[CRdata].v = &crm;
		alts[CRdata].op = CHANRCV;
		alts[CRflush].c = x->flushc;
		alts[CRflush].v = nil;
		alts[CRflush].op = CHANRCV;
		alts[NMR].op = CHANEND;

		switch(alt(alts)){
		case CRdata:
			break;
		case CRflush:
			filsyscancel(x);
			return;
		}

		/* received data */
		x->flushtag = -1;
		c1 = crm.c1;
		c2 = crm.c2;
		t = malloc(cnt+UTFmax+1);	/* room to unpack partial rune plus */
		pair.s = t;
		pair.ns = cnt;
		send(c1, &pair);
		if(x->flushing){
			recv(x->flushc, nil);	/* wake up flushing xfid */
			recv(c2, nil);			/* wake up window and toss data */
			free(t);
			filsyscancel(x);
			return;
		}
		qlock(&x->active);
		recv(c2, &pair);
		fc.data = pair.s;
		fc.count = pair.ns;
		filsysrespond(x->fs, x, &fc, nil);
		free(t);
		qunlock(&x->active);
		break;

	case Qlabel:
		n = strlen(w->label);
		if(off > n)
			off = n;
		if(off+cnt > n)
			cnt = n-off;
		fc.data = w->label+off;
		fc.count = cnt;
		filsysrespond(x->fs, x, &fc, nil);
		break;

	case Qmouse:
		x->flushtag = x->tag;

		alts[MRdata].c = w->mouseread;
		alts[MRdata].v = &mrm;
		alts[MRdata].op = CHANRCV;
		alts[MRflush].c = x->flushc;
		alts[MRflush].v = nil;
		alts[MRflush].op = CHANRCV;
		alts[NMR].op = CHANEND;

		switch(alt(alts)){
		case MRdata:
			break;
		case MRflush:
			filsyscancel(x);
			return;
		}

		/* received data */
		x->flushtag = -1;
		if(x->flushing){
			recv(x->flushc, nil);		/* wake up flushing xfid */
			recv(mrm.cm, nil);			/* wake up window and toss data */
			filsyscancel(x);
			return;
		}
		qlock(&x->active);
		recv(mrm.cm, &ms);
		c = 'm';
		if(w->resized)
			c = 'r';
		n = sprint(buf, "%c%11d %11d %11d %11ld ", c, ms.xy.x, ms.xy.y, ms.buttons, ms.msec);
		w->resized = 0;
		fc.data = buf;
		fc.count = min(n, cnt);
		filsysrespond(x->fs, x, &fc, nil);
		qunlock(&x->active);
		break;

	case Qcursor:
		filsysrespond(x->fs, x, &fc, "cursor read not implemented");
		break;

	/* The algorithm for snarf and text is expensive but easy and rarely used */
	case Qsnarf:
		getsnarf();
		if(nsnarf)
			t = runetobyte(snarf, nsnarf, &n);
		else {
			t = nil;
			n = 0;
		}
		goto Text;

	case Qtext:
		t = wcontents(w, &n);
		goto Text;

	Text:
		if(off > n){
			off = n;
			cnt = 0;
		}
		if(off+cnt > n)
			cnt = n-off;
		fc.data = t+off;
		fc.count = cnt;
		filsysrespond(x->fs, x, &fc, nil);
		free(t);
		break;

	case Qwdir:
		t = estrdup(w->dir);
		n = strlen(t);
		goto Text;

	case Qwinid:
		n = sprint(buf, "%11d ", w->id);
		t = estrdup(buf);
		goto Text;


	case Qwinname:
		n = strlen(w->name);
		if(n == 0){
			filsysrespond(x->fs, x, &fc, "window has no name");
			break;
		}
		t = estrdup(w->name);
		goto Text;

	case Qwindow:
		i = w->i;
		if(i == nil || Dx(w->screenr)<=0){
			filsysrespond(x->fs, x, &fc, Enowindow);
			return;
		}
		r = w->screenr;
		goto caseImage;

	case Qscreen:
		i = display->image;
		if(i == nil){
			filsysrespond(x->fs, x, &fc, "no top-level screen");
			break;
		}
		r = i->r;
		/* fall through */

	caseImage:
		if(off < 5*12){
			n = sprint(buf, "%11s %11d %11d %11d %11d ",
				chantostr(cbuf, screen->chan),
				i->r.min.x, i->r.min.y, i->r.max.x, i->r.max.y);
			t = estrdup(buf);
			goto Text;
		}
		t = malloc(cnt);
		fc.data = t;
		n = readwindow(i, t, r, off, cnt);	/* careful; fc.count is unsigned */
		if(n < 0){
			buf[0] = 0;
			errstr(buf, sizeof buf);
			filsysrespond(x->fs, x, &fc, buf);
		}else{
			fc.count = n;
			filsysrespond(x->fs, x, &fc, nil);
		}
		free(t);
		return;

	case Qwctl:	/* read returns rectangle, hangs if not resized */
		if(cnt < 4*12){
			filsysrespond(x->fs, x, &fc, Etooshort);
			break;
		}
		x->flushtag = x->tag;

		alts[WCRdata].c = w->wctlread;
		alts[WCRdata].v = &cwrm;
		alts[WCRdata].op = CHANRCV;
		alts[WCRflush].c = x->flushc;
		alts[WCRflush].v = nil;
		alts[WCRflush].op = CHANRCV;
		alts[NMR].op = CHANEND;

		switch(alt(alts)){
		case WCRdata:
			break;
		case WCRflush:
			filsyscancel(x);
			return;
		}

		/* received data */
		x->flushtag = -1;
		c1 = cwrm.c1;
		c2 = cwrm.c2;
		t = malloc(cnt+1);	/* be sure to have room for NUL */
		pair.s = t;
		pair.ns = cnt+1;
		send(c1, &pair);
		if(x->flushing){
			recv(x->flushc, nil);	/* wake up flushing xfid */
			recv(c2, nil);			/* wake up window and toss data */
			free(t);
			filsyscancel(x);
			return;
		}
		qlock(&x->active);
		recv(c2, &pair);
		fc.data = pair.s;
		if(pair.ns > cnt)
			pair.ns = cnt;
		fc.count = pair.ns;
		filsysrespond(x->fs, x, &fc, nil);
		free(t);
		qunlock(&x->active);
		break;

	default:
		fprint(2, "unknown qid %d in read\n", qid);
		sprint(buf, "unknown qid in read");
		filsysrespond(x->fs, x, &fc, buf);
		break;
	}
}