Fixed properties defined on prototype in Safari background page proxy

safari/ext/content.js

 /*
  * This file is part of Adblock Plus <http://adblockplus.org/>,
  * Copyright (C) 2006-2013 Eyeo GmbH
  *
  * Adblock Plus is free software: you can redistribute it and/or modify
  * it under the terms of the GNU General Public License version 3 as
  * published by the Free Software Foundation.
  *
  * Adblock Plus is distributed in the hope that it will be useful,
  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  * GNU General Public License for more details.
  *
  * You should have received a copy of the GNU General Public License
  * along with Adblock Plus.  If not, see <http://www.gnu.org/licenses/>.
  */
 
 (function()
 {
   safari.self.tab.dispatchMessage("loading", document.location.href);
 
 
   /* Background page proxy */
+
+  var beforeLoadEvent = document.createEvent("Event");
+  beforeLoadEvent.initEvent("beforeload");
+
   var proxy = {
     objects: [],
     callbacks: [],
 
     send: function(message)
     {
-      var evt = document.createEvent("Event");
-      evt.initEvent("beforeload");
-      return safari.self.tab.canLoad(evt, {type: "proxy", payload: message});
+      return safari.self.tab.canLoad(beforeLoadEvent, {type: "proxy", payload: message});
     },
     checkResult: function(result)
     {
       if (!result.succeed)
         throw result.error;
     },
     deserializeResult: function(result)
     {
       this.checkResult(result);
       return this.deserialize(result.result);
     },
     serialize: function(obj, memo)
     {
-      var objectId = this.objects.indexOf(obj);
+      var objectId = this.getObjectId(obj);
       if (objectId != -1)
         return {type: "hosted", objectId: objectId};
 
       if (typeof obj == "function")
       {
         var callbackId = this.callbacks.indexOf(obj);
 
         if (callbackId == -1)
         {
           callbackId = this.callbacks.push(obj) - 1;
 
-          safari.self.addEventListener("message", function(event)
+          if (callbackId == 0)

[Wladimir Palant, 2014/01/15 16:21:01]

This is non-obvious and needs a short explanation in a comment, something like
"Only add a listener for the first callback, after that we can simply assume
that it is already there."

           {
-            if (event.name == "proxyCallback")
-            if (event.message.callbackId == callbackId)
-              obj.apply(
-                this.getObject(event.message.contextId),
-                this.deserializeSequence(event.message.args)
-              );
-          }.bind(this));
+            safari.self.addEventListener("message", function(event)
+            {
+              if (event.name == "proxyCallback")
+              {
+                this.callbacks[event.message.callbackId].apply(
+                  this.getObject(event.message.contextId),
+                  this.deserializeSequence(event.message.args)
+                );
+              }
+            }.bind(this));
+          }
         }
 
         return {type: "callback", callbackId: callbackId};
       }
 
       if (typeof obj == "object" &&
           obj != null &&
           obj.constructor != Date &&
           obj.constructor != RegExp)
       {
@@ skipping 117 matching lines @@
             functionId: objectId,
             contextId: proxy.getObjectId(this),
             args: Array.prototype.map.call(
               arguments,
               proxy.serialize.bind(proxy)
             )
           })
         );
       };
     },
-    getObject: function(objectId) {
+    getObject: function(objectId)
+    {
       var objectInfo = this.send({
         type: "inspectObject",
         objectId: objectId
       });
 
       var obj = this.objects[objectId];
       if (obj)
         Object.getOwnPropertyNames(obj).forEach(function(prop) { delete obj[prop]; });
       else
       {
         if (objectInfo.isFunction)
           obj = this.createFunction(objectId);
         else
           obj = {};
 
         this.objects[objectId] = obj;
       }
 
       var ignored = [];
       if ("prototypeOf" in objectInfo)
       {
         var prototype = window[objectInfo.prototypeOf].prototype;
 
         ignored = Object.getOwnPropertyNames(prototype);
         ignored.splice(ignored.indexOf("constructor"), 1);

[Wladimir Palant, 2014/01/15 16:21:01]

The assumption here is that ignored.indexOf() will never return -1. I'd rather
drop that assumption and check explicitly.

 
         obj.__proto__ = prototype;
       }
       else
       {
         if (objectInfo.isFunction)
+        {
           ignored = Object.getOwnPropertyNames(function() {});
+          ignored.splice(ignored.indexOf("prototype"), 1);
+        }
         else
           ignored = [];
 
         if ("prototypeId" in objectInfo)
           obj.__proto__ = this.getObject(objectInfo.prototypeId);
         else
           obj.__proto__ = null;
       }
 
       for (var property in objectInfo.properties)
-        if (ignored.indexOf(property) == -1)
+      {
+        if (ignored.indexOf(property) != -1)
+          continue;
+
+        if (!Object.hasOwnProperty(obj, property) || Object.getOwnPropertyDescriptor(obj, property).configurable)
+        {
           Object.defineProperty(obj, property, this.createProperty(
             property, objectInfo.properties[property].enumerable
           ));
-
-      if (objectInfo.isFunction)
-        obj.prototype = this.getProperty(objectId, "prototype");
+        }
+        else
+          obj[property] = this.getProperty(objectId, property);
+      }
 
       return obj;
     }
   };
 
 
   /* Web request blocking */
 
   document.addEventListener("beforeload", function(event)
   {
     var type;
 
-    switch(event.target.nodeName)
+    switch(event.target.localName)
     {
-      case "FRAME":
-      case "IFRAME":
+      case "frame":
+      case "iframe":
         type = "frame";
         break;
-      case "IMG":
+      case "img":
         type = "image";
         break;
-      case "OBJECT":
-      case "EMBED":
+      case "object":
+      case "embed":
         type = "object";
         break;
-      case "SCRIPT":
+      case "script":
         type = "script";
         break;
-      case "LINK":
-        if (/(^|\s)stylesheet($|\s)/i.test(event.target.rel))
+      case "link":
+        if (/\bstylesheet\b/i.test(event.target.rel))
         {
           type = "stylesheet";
           break;
         }
       default:
         type = "other";
     }
 
     if (!safari.self.tab.canLoad(event, {type: "webRequest", payload: {url: event.url, type: type}}))
       event.preventDefault();
   }, true);
 
 
   /* API */
 
   ext.backgroundPage = {
     _eventTarget: safari.self,
     _messageDispatcher: safari.self.tab,
 
     sendMessage: sendMessage,
     getWindow: function() { return proxy.getObject(0); }
   };
 
   ext.onMessage = new MessageEventTarget(safari.self);
 })();