[gnome-shell] screenshot: Extend ScreenshotArea parameter validation

[Florian Müllner <fmuellner src gnome org>]

commit f9f500490974e4bf5c4824fa596ae133995bb7ef
Author: Florian Müllner <fmuellner gnome org>
Date:   Mon Nov 4 11:14:44 2013 +0100

    screenshot: Extend ScreenshotArea parameter validation
    
    We currently only ensure that width and height are positive, so it
    is still possible to pass in values that don't make any sense at all
    (which may even result in a crash when exceeding limits imposed by
    X11).
    There is nothing to screenshot outside the actual screen area, so
    restrict the parameters to that.
    
    https://bugzilla.gnome.org/show_bug.cgi?id=699752

 js/ui/screenshot.js |    4 +++-
 1 files changed, 3 insertions(+), 1 deletions(-)
---
diff --git a/js/ui/screenshot.js b/js/ui/screenshot.js
index 10435c5..73ca773 100644
--- a/js/ui/screenshot.js
+++ b/js/ui/screenshot.js
@@ -79,7 +79,9 @@ const ScreenshotService = new Lang.Class({
 
     ScreenshotAreaAsync : function (params, invocation) {
         let [x, y, width, height, flash, filename, callback] = params;
-        if (height <= 0 || width <= 0) {
+        if (x < 0 || y < 0 ||
+            width <= 0 || height <= 0 ||
+            x + width > global.screen_width || y + height > global.screen_height) {
             invocation.return_error_literal(Gio.IOErrorEnum, Gio.IOErrorEnum.CANCELLED,
                         "Invalid params");
             return;