fix double free bug, simplify error handling, reduce X11 calls, improve style

src/cmd/rio/winwatch.c

@@ -24,6 +24,7 @@ struct Win {
 
 XDisplay *dpy;
 XWindow root;
+
 Atom net_active_window;
 Reprog *exclude = nil;
 Win *win;
@@ -36,14 +37,13 @@ int showwmnames;
 Font *font;
 Image *lightblue;
 
-XErrorHandler oldxerrorhandler;
 
-enum {
+enum 
+{
 	PAD = 3,
 	MARGIN = 5
 };
 
-static jmp_buf savebuf;
 
 int
 winwatchxerrorhandler(XDisplay *disp, XErrorEvent *xe)
@@ -53,11 +53,7 @@ winwatchxerrorhandler(XDisplay *disp, XErrorEvent *xe)
 	XGetErrorText(disp, xe->error_code, buf, 100);
 	fprint(2, "winwatch: X error %s, request code %d\n",
 	    buf, xe->request_code);
-	XFlush(disp);
+	return 0;  
-	XSync(disp, False);
-	XSetErrorHandler(oldxerrorhandler);
-	longjmp(savebuf, 1);
-	return(0);  /* Not reached */
 }
 
 void*
@@ -75,7 +71,7 @@ estrdup(char *s)
 	s = strdup(s);
 	if(s == nil)
 		sysfatal("out of memory allocating");
-	return(s);
+	return s;
 }
 
 char*
@@ -89,18 +85,15 @@ getproperty(XWindow w, Atom a)
 
 	n = 100;
 	p = nil;
-	oldxerrorhandler = XSetErrorHandler(winwatchxerrorhandler);
 	s = XGetWindowProperty(dpy, w, a, 0, 100L, 0,
 	    AnyPropertyType, &type, &fmt, &n, &dummy, &p);
-	XFlush(dpy);
+
-	XSync(dpy, False);
-	XSetErrorHandler(oldxerrorhandler);
 	if(s != 0){
 		XFree(p);
-		return(nil);
+		return nil;
 	}
 
-	return((char*)p);
+	return (char*)p;
 }
 
 XWindow
@@ -108,7 +101,7 @@ findname(XWindow w)
 {
 	int i;
 	uint nxwin;
-	XWindow dw1, dw2, *xwin;
+	XWindow dw1, dw2, *xwin, rwin;
 	char *p;
 	int s;
 	Atom net_wm_name;
@@ -116,37 +109,32 @@ findname(XWindow w)
 	p = getproperty(w, XA_WM_NAME);
 	if(p){
 		free(p);
-		return(w);
+		return w;
 	}
 
 	net_wm_name = XInternAtom(dpy, "_NET_WM_NAME", FALSE);
 	p = getproperty(w, net_wm_name);
 	if(p){
 		free(p);
-		return(w);
+		return w;
 	}
 
-	oldxerrorhandler = XSetErrorHandler(winwatchxerrorhandler);
+	rwin = 0;
+
 	s = XQueryTree(dpy, w, &dw1, &dw2, &xwin, &nxwin);
-	XFlush(dpy);
-	XSync(dpy, False);
-	XSetErrorHandler(oldxerrorhandler);
-	if(s == 0) {
-		if (xwin != NULL)
-			XFree(xwin);
-		return 0;
-	}
 
+	if(s != 0){	
 		for (i = 0; i < nxwin; i++){
 		w = findname(xwin[i]);
 		if(w != 0){
-			XFree(xwin);
+			rwin = w;
-			return w;
+			break ;
 		}
 		}
 	XFree(xwin); 
+	}
 
-	return 0;
+	return rwin;
 }
 
 int
@@ -156,7 +144,6 @@ wcmp(const void *w1, const void *w2)
 }
 
 /* unicode-aware case-insensitive strcmp,  taken from golang’s gc/subr.c */
-
 int
 _cistrcmp(char *p, char *q)
 {
@@ -200,17 +187,14 @@ refreshwin(void)
 	Status s;
 	Atom net_wm_name;
 
-
-	oldxerrorhandler = XSetErrorHandler(winwatchxerrorhandler);
 	s = XQueryTree(dpy, root, &dw1, &dw2, &xwin, &nxwin);
-	XFlush(dpy);
+
-	XSync(dpy, False);
-	XSetErrorHandler(oldxerrorhandler);
 	if(s == 0){
 		if(xwin != NULL)
 			XFree(xwin);
 		return;
 	}
+
 	qsort(xwin, nxwin, sizeof(xwin[0]), wcmp);
 
 	nw = 0;
@@ -220,11 +204,8 @@ refreshwin(void)
 		if(xwin[i] == 0)
 			continue;
 
-		oldxerrorhandler = XSetErrorHandler(winwatchxerrorhandler);
 		s = XGetWindowAttributes(dpy, xwin[i], &attr);
-		XFlush(dpy);
+
-		XSync(dpy, False);
-		XSetErrorHandler(oldxerrorhandler);
 		if(s == 0)
 			continue;
 		if(attr.width <= 0 ||
@@ -232,11 +213,7 @@ refreshwin(void)
 		    attr.map_state != IsViewable)
 			continue;
 
-		oldxerrorhandler = XSetErrorHandler(winwatchxerrorhandler);
 		s = XGetClassHint(dpy, xwin[i], &class);
-		XFlush(dpy);
-		XSync(dpy, False);
-		XSetErrorHandler(oldxerrorhandler);
 
 		if(s == 0)
 			continue;
@@ -280,6 +257,7 @@ refreshwin(void)
 			mwin += 8;
 			win = erealloc(win, mwin * sizeof(win[0]));
 		}
+
 		win[nw].n = xwin[i];
 		win[nw].label = estrdup(label);
 		win[nw].dirty = 1;
@@ -290,11 +268,7 @@ refreshwin(void)
 		nw++;
 	}
 
-	oldxerrorhandler = XSetErrorHandler(winwatchxerrorhandler);
 	XFree(xwin); 
-	XFlush(dpy);
-	XSync(dpy, False);
-	XSetErrorHandler(oldxerrorhandler);
 
 	while(nwin > nw)
 		free(win[--nwin].label);
@@ -481,9 +455,6 @@ main(int argc, char **argv)
 	if(argc)
 	    usage();
 
-	/* moved up from original winwatch.c for p9p because there can be only one but we want to restart when needed */
-	einit(Emouse | Ekeyboard);
-	Etimer = etimer(0, 1000);
 
 	dpy = XOpenDisplay("");
 	if(dpy == nil)
@@ -500,11 +471,14 @@ main(int argc, char **argv)
 	if(font == nil)
 		sysfatal("font '%s' not found", fontname);
 
-	/* reentry point upon X server errors */
+	einit(Emouse | Ekeyboard);
-	setjmp(savebuf);
+	Etimer = etimer(0, 1000);
+
+	XSetErrorHandler(winwatchxerrorhandler);
 
 	refreshwin();
 	redraw(screen, 1);
+
 	for(;;){
 		switch(eread(Emouse|Ekeyboard|Etimer, &e)){
 		case Ekeyboard: