rio: implement "look" (thanks lf94)

sys/src/cmd/rio/dat.h

@@ -210,6 +210,7 @@ void		wmousectl(Window*);
 void		wmovemouse(Window*, Point);
 void		wpaste(Window*);
 void		wplumb(Window*);
+void		wlook(Window*);
 void		wrefresh(Window*, Rectangle);
 void		wrepaint(Window*);
 void		wresize(Window*, Image*, int);

sys/src/cmd/rio/rio.c

@@ -62,6 +62,7 @@ enum
 	Paste,
 	Snarf,
 	Plumb,
+	Look,
 	Send,
 	Scroll,
 };
@@ -71,6 +72,7 @@ char		*menu2str[] = {
  [Paste]		"paste",
  [Snarf]		"snarf",
  [Plumb]		"plumb",
+ [Look]		"look",
  [Send]		"send",
  [Scroll]		"scroll",
 			nil
@@ -816,6 +818,10 @@ button2menu(Window *w)
 		wplumb(w);
 		break;
 
+	case Look:
+		wlook(w);
+		break;
+
 	case Send:
 		getsnarf();
 		wsnarf(w);

sys/src/cmd/rio/wind.c

@@ -889,6 +889,28 @@ wplumb(Window *w)
 	plumbfree(m);
 }
 
+void
+wlook(Window *w)
+{
+	int i, n, e;
+
+	i = w->q1;
+	n = i - w->q0;
+	e = w->nr - n;
+	if(n <= 0 || e < n)
+		return;
+
+	while(runestrncmp(w->r+w->q0, w->r+i, n) != 0){
+		if(i < e)
+			i++;
+		else
+			i = 0;
+	}
+
+	wsetselect(w, i, i+n);
+	wshow(w, i);
+}
+
 int
 winborder(Window *w, Point xy)
 {