Issue 1296 - Add SetUpdateAvailableCallback

src/FilterEngine.cpp

 /*
  * This file is part of Adblock Plus <http://adblockplus.org/>,
  * Copyright (C) 2006-2014 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
@@ skipping 338 matching lines @@
 }
 
 void FilterEngine::RemoveUpdateAvailableCallback()
 {
   jsEngine->RemoveEventCallback("updateAvailable");
 }
 
 void FilterEngine::UpdateAvailable(
     FilterEngine::UpdateAvailableCallback callback, JsValueList& params)
 {
-  callback(params[0]->AsString());

[Wladimir Palant, 2014/09/18 19:44:17]

I'd rather not crash if the JS code unexpectedly doesn't specify any parameters.
So maybe:

  std::string url = (params.size() >= 1 ? params[0]->AsString : "");
  callback(url);

[Felix Dahlke, 2014/09/19 02:51:41]

Knowing that the updater actually ensures a valid URL here, it does seem
appropriate to crash hard. I'm not really happy with passing "" to (possibly
slightly naive) updater callbacks.

Then again, we can achieve this without crashing - by simply not invoking the
callback if the URL is missing. Will do that.

+  if (params.size() >= 1 && !params[0]->IsNull())
+    callback(params[0]->AsString());
 }
 
 void FilterEngine::ForceUpdateCheck(
     FilterEngine::UpdateCheckDoneCallback callback)
 {
   std::string eventName = "updateCheckDone";
   eventName += ++updateCheckId;
 
   jsEngine->SetEventCallback(eventName, std::tr1::bind(&FilterEngine::UpdateCheckDone,
       this, eventName, callback, std::tr1::placeholders::_1));
@@ skipping 32 matching lines @@
 }
 
 int FilterEngine::CompareVersions(const std::string& v1, const std::string& v2)
 {
   JsValueList params;
   params.push_back(jsEngine->NewValue(v1));
   params.push_back(jsEngine->NewValue(v2));
   JsValuePtr func = jsEngine->Evaluate("API.compareVersions");
   return func->Call(params)->AsInt();
 }