rio: preserve window z-order on resize, fix race conditions

sort the window array by w->topped before reshaping all
windows. this preserves the window z-order.

remove implicit focus change on reshape/move. it called
wcurrent() in wtcl thread which might send a wctl message
to itself, bad... also we might not want to change focus
on reshape, like for the rio resize. so we set the input
window explicitely in all call sites.

window deletion was racy. wclosewin() destroys w->i, but
it is called outside the wctl thread so it might just
free the image under libframe doing some text selection.
this is fixed the following: add wclunk() function,
which basically just marks the window as deleted and
removes the reference from the window[] and hidden[]
arrays. (called on wclose() when refcount drops to
zero). wclosewin() now just frees the image and is only
called from the wctl thread on exit or when handing
the Deleted message.

get a reference to the window when doing sweeping or
moving as the filesystem might just clunk it under
us and we might end up sending wctl messages to
a Exited window.

wctl resize message has to fail if the window is not
current as it might be hidden... would also be annoying.

1 files changed, 101 insertions, 69 deletions

diff --git a/sys/src/cmd/rio/rio.c b/sys/src/cmd/rio/rio.c
index 87137e483..98d3dd10b 100644
--- a/sys/src/cmd/rio/rio.c
+++ b/sys/src/cmd/rio/rio.c
@@ -347,7 +347,7 @@ keyboardthread(void*)
 	while(s = recvp(kbdchan)){
 		if(*s == 'k' || *s == 'K')
 			shiftdown = utfrune(s+1, Kshift) != nil;
-		if(input == nil || sendp(input->ck, s) <= 0)
+		if(input == nil || input->deleted || sendp(input->ck, s) <= 0)
 			free(s);
 	}
 }
@@ -470,7 +470,7 @@ void
 mousethread(void*)
 {
 	int sending, inside, scrolling, moving, band;
-	Window *oin, *w, *winput;
+	Window *w, *winput;
 	Image *i;
 	Rectangle r;
 	Point xy;
@@ -513,7 +513,7 @@ mousethread(void*)
 				wtopme(wkeyboard);
 				winput = wkeyboard;
 			}
-			if(winput!=nil && winput->i!=nil){
+			if(winput!=nil && !winput->deleted && winput->i!=nil){
 				/* convert to logical coordinates */
 				xy.x = mouse->xy.x + (winput->i->r.min.x-winput->screenr.min.x);
 				xy.y = mouse->xy.y + (winput->i->r.min.y-winput->screenr.min.y);
@@ -555,7 +555,7 @@ mousethread(void*)
 			else
 				riosetcursor(nil, 0);
 			if(moving && (mouse->buttons&7)){
-				oin = winput;
+				incref(winput);
 				band = mouse->buttons & 3;
 				sweeping = 1;
 				if(band)
@@ -564,18 +564,19 @@ mousethread(void*)
 					i = drag(winput, &r);
 				sweeping = 0;
 				if(i != nil){
-					if(winput == oin){
-						if(band)
-							wsendctlmesg(winput, Reshaped, i->r, i);
-						else
-							wsendctlmesg(winput, Moved, r, i);
-						cornercursor(winput, mouse->xy, 1);
-					}else
-						freeimage(i);
+					if(band)
+						wsendctlmesg(winput, Reshaped, i->r, i);
+					else
+						wsendctlmesg(winput, Moved, r, i);
+					cornercursor(winput, mouse->xy, 1);
+				}
+				if(wclose(winput) == 0)
+					w = winput;
+				else {
+					riosetcursor(nil, 0);
+					w = nil;
 				}
 			}
-			if(w != nil)
-				cornercursor(w, mouse->xy, 0);
 			/* we're not sending the event, but if button is down maybe we should */
 			if(mouse->buttons){
 				/* w->topped will be zero or less if window has been bottomed */
@@ -583,8 +584,11 @@ mousethread(void*)
 					if(mouse->buttons & 1){
 						;
 					}else if(mouse->buttons & 2){
-						if(winput && !winput->mouseopen)
+						if(winput && !winput->deleted && !winput->mouseopen){
+							incref(winput);
 							button2menu(winput);
+							wclose(winput);
+						}
 					}else if(mouse->buttons & 4)
 						button3menu();
 				}else{
@@ -607,11 +611,17 @@ mousethread(void*)
 		}
 }
 
+int
+wtopcmp(void *a, void *b)
+{
+	return (*(Window**)a)->topped - (*(Window**)b)->topped;
+}
+
 void
 resized(void)
 {
 	Image *im;
-	int i, j, ishidden;
+	int i, j;
 	Rectangle r;
 	Point o, n;
 	Window *w;
@@ -627,10 +637,9 @@ resized(void)
 	draw(view, view->r, background, nil, ZP);
 	o = subpt(viewr.max, viewr.min);
 	n = subpt(view->clipr.max, view->clipr.min);
+	qsort(window, nwindow, sizeof(window[0]), wtopcmp);
 	for(i=0; i<nwindow; i++){
 		w = window[i];
-		if(w->deleted)
-			continue;
 		r = rectsubpt(w->i->r, viewr.min);
 		r.min.x = (r.min.x*n.x)/o.x;
 		r.min.y = (r.min.y*n.y)/o.y;
@@ -639,26 +648,25 @@ resized(void)
 		if(!goodrect(r))
 			r = rectsubpt(w->i->r, viewr.min);
 		r = rectaddpt(r, screen->clipr.min);
-		ishidden = 0;
 		for(j=0; j<nhidden; j++)
-			if(w == hidden[j]){
-				ishidden = 1;
+			if(w == hidden[j])
 				break;
-			}
-		if(ishidden){
+		incref(w);
+		if(j < nhidden){
 			im = allocimage(display, r, screen->chan, 0, DWhite);
 			r = ZR;
-		}else
+		} else
 			im = allocwindow(wscreen, r, Refbackup, DWhite);
 		if(im)
 			wsendctlmesg(w, Reshaped, r, im);
+		wclose(w);
 	}
 	viewr = screen->r;
 	flushimage(display, 1);
 }
 
-static int
-wcovered(Window *w, Rectangle r, int i)
+int
+obscured(Window *w, Rectangle r, int i)
 {
 	Window *t;
 
@@ -668,21 +676,21 @@ wcovered(Window *w, Rectangle r, int i)
 		return 1;
 	for(; i<nwindow; i++){
 		t = window[i];
-		if(t == w || t->topped <= w->topped || t->deleted)
+		if(t == w || t->topped <= w->topped)
 			continue;
 		if(Dx(t->screenr) == 0 || Dy(t->screenr) == 0 || rectXrect(r, t->screenr) == 0)
 			continue;
 		if(r.min.y < t->screenr.min.y)
-			if(!wcovered(w, Rect(r.min.x, r.min.y, r.max.x, t->screenr.min.y), i))
+			if(!obscured(w, Rect(r.min.x, r.min.y, r.max.x, t->screenr.min.y), i))
 				return 0;
 		if(r.min.x < t->screenr.min.x)
-			if(!wcovered(w, Rect(r.min.x, r.min.y, t->screenr.min.x, r.max.y), i))
+			if(!obscured(w, Rect(r.min.x, r.min.y, t->screenr.min.x, r.max.y), i))
 				return 0;
 		if(r.max.y > t->screenr.max.y)
-			if(!wcovered(w, Rect(r.min.x, t->screenr.max.y, r.max.x, r.max.y), i))
+			if(!obscured(w, Rect(r.min.x, t->screenr.max.y, r.max.x, r.max.y), i))
 				return 0;
 		if(r.max.x > t->screenr.max.x)
-			if(!wcovered(w, Rect(t->screenr.max.x, r.min.y, r.max.x, r.max.y), i))
+			if(!obscured(w, Rect(t->screenr.max.x, r.min.y, r.max.x, r.max.y), i))
 				return 0;
 		return 1;
 	}
@@ -699,13 +707,12 @@ button3menu(void)
 		for(j=0; j<n; j++)
 			if(window[i] == hidden[j])
 				break;
-		if(j < n || window[i]->deleted)
-			continue;
-		if(wcovered(window[i], window[i]->screenr, 0)){
-			hidden[n++] = window[i];
-			if(n >= nelem(hidden))
-				break;
-		}
+		if(j == n)
+			if(obscured(window[i], window[i]->screenr, 0)){
+				hidden[n++] = window[i];
+				if(n >= nelem(hidden))
+					break;
+			}
 	}
 	if(n >= nelem(menu3str)-Hidden)
 		n = nelem(menu3str)-Hidden-1;
@@ -752,9 +759,6 @@ button3menu(void)
 void
 button2menu(Window *w)
 {
-	if(w->deleted)
-		return;
-	incref(w);
 	if(w->scrolling)
 		menu2str[Scroll] = "noscroll";
 	else
@@ -803,7 +807,6 @@ button2menu(Window *w)
 			wshow(w, w->nr);
 		break;
 	}
-	wclose(w);
 	wsendctlmesg(w, Wakeup, ZR, nil);
 	flushimage(display, 1);
 }
@@ -1113,9 +1116,13 @@ resize(void)
 	w = pointto(TRUE);
 	if(w == nil)
 		return;
+	incref(w);
 	i = sweep();
-	if(i)
+	if(i){
 		wsendctlmesg(w, Reshaped, i->r, i);
+		wcurrent(w);
+	}
+	wclose(w);
 }
 
 void
@@ -1128,10 +1135,14 @@ move(void)
 	w = pointto(FALSE);
 	if(w == nil)
 		return;
+	incref(w);
 	i = drag(w, &r);
-	if(i)
+	if(i){
 		wsendctlmesg(w, Moved, r, i);
-	cornercursor(input, mouse->xy, 1);
+		wcurrent(w);
+	}
+	cornercursor(w, mouse->xy, 1);
+	wclose(w);
 }
 
 int
@@ -1145,38 +1156,39 @@ whide(Window *w)
 			return -1;
 	if(nhidden >= nelem(hidden))
 		return 0;
+	incref(w);
 	i = allocimage(display, w->screenr, w->i->chan, 0, DWhite);
 	if(i){
+		if(w == input)
+			input = nil;
 		hidden[nhidden++] = w;
 		wsendctlmesg(w, Reshaped, ZR, i);
-		return 1;
 	}
-	return 0;
+	wclose(w);
+	return i!=0;
 }
 
 int
-wunhide(int h)
+wunhide(Window *w)
 {
+	int j;
 	Image *i;
-	Window *w;
 
-	w = hidden[h];
-	if(w == nil)
-		return 0;
-	if(h >= nhidden){
-		wtopme(w);
-		wcurrent(w);
-		flushimage(display, 1);
-		return 1;
-	}
+	for(j=0; j<nhidden; j++)
+		if(hidden[j] == w)
+			break;
+	if(j == nhidden)
+		return -1;	/* not hidden */
+	incref(w);
 	i = allocwindow(wscreen, w->i->r, Refbackup, DWhite);
 	if(i){
 		--nhidden;
-		memmove(hidden+h, hidden+h+1, (nhidden-h)*sizeof(Window*));
+		memmove(hidden+j, hidden+j+1, (nhidden-j)*sizeof(Window*));
 		wsendctlmesg(w, Reshaped, w->i->r, i);
-		return 1;
+		wcurrent(w);
 	}
-	return 0;
+	wclose(w);
+	return i!=0;
 }
 
 void
@@ -1185,16 +1197,34 @@ hide(void)
 	Window *w;
 
 	w = pointto(TRUE);
-	if(w == nil)
-		return;
-	whide(w);
+	if(w)
+		whide(w);
 }
 
 void
-unhide(int h)
+unhide(int j)
 {
-	if(h >= Hidden)
-		wunhide(h - Hidden);
+	Window *w;
+
+	if(j < Hidden)
+		return;
+	j -= Hidden;
+	w = hidden[j];
+	if(w == nil)
+		return;
+	if(j < nhidden){
+		wunhide(w);
+		return;
+	}
+	/* uncover obscured window */
+	for(j=0; j<nwindow; j++)
+		if(window[j] == w){
+			incref(w);
+			wcurrent(w);
+			wtopme(w);
+			wclose(w);
+			return;
+		}
 }
 
 Window*
@@ -1207,6 +1237,10 @@ new(Image *i, int hideit, int scrollit, int pid, char *dir, char *cmd, char **ar
 
 	if(i == nil)
 		return nil;
+	if(hideit && nhidden >= nelem(hidden)){
+		freeimage(i);
+		return nil;
+	}
 	cm = chancreate(sizeof(Mouse), 0);
 	ck = chancreate(sizeof(char*), 0);
 	cctl = chancreate(sizeof(Wctlmesg), 4);
@@ -1221,8 +1255,6 @@ new(Image *i, int hideit, int scrollit, int pid, char *dir, char *cmd, char **ar
 	free(mc);	/* wmk copies *mc */
 	window = erealloc(window, ++nwindow*sizeof(Window*));
 	window[nwindow-1] = w;
-	if(nhidden >= nelem(hidden))
-		hideit = 0;
 	if(hideit){
 		hidden[nhidden++] = w;
 		w->screenr = ZR;