Fix ATL assertion error in traverser

src/plugin/PluginFilter.cpp

 #include "PluginStdAfx.h"
 
 #include "PluginFilter.h"
 
 #if (defined PRODUCT_ADBLOCKPLUS)
 #include "PluginSettings.h"
 #include "PluginClient.h"
 #include "PluginClientFactory.h"
 #endif
 
@@ skipping 369 matching lines @@
   {
     CComPtr<IHTMLElement> pDomPredecessor;
     HRESULT hr = S_FALSE;
     switch (m_predecessor->m_type)
     {
     case ETraverserComplexType::TRAVERSER_TYPE_PARENT:
       hr = pEl->get_parentElement(&pDomPredecessor);
       break;
     case ETraverserComplexType::TRAVERSER_TYPE_IMMEDIATE:
       hr = S_FALSE;
-      CComQIPtr<IHTMLDOMNode> pDomNode = pEl;
-      if (pDomNode)
+      CComQIPtr<IHTMLDOMNode> pPrevSiblingNode = pEl;
+      if (pPrevSiblingNode)
       {
-        CComPtr<IHTMLDOMNode> pPrevSiblingNode = pDomNode;
         long type;
         do
         {
-          pPrevSiblingNode->get_previousSibling(&pPrevSiblingNode);
+          IHTMLDOMNode* tmpNode;
+          pPrevSiblingNode->get_previousSibling(&tmpNode);
+          pPrevSiblingNode.Attach(tmpNode);

[Wladimir Palant, 2013/10/08 10:30:38]

For reference: this is the only place that needed to be changed, the rest is
just cleanup.

           if (pPrevSiblingNode)
           {
             hr = pPrevSiblingNode->get_nodeType(&type);
             if (hr != S_OK)
-              pPrevSiblingNode = NULL;
+              pPrevSiblingNode.Release();
           }
         } while (pPrevSiblingNode && type != 1);
 
         if (pPrevSiblingNode)
           hr = pPrevSiblingNode.QueryInterface(&pDomPredecessor);
         else
           return false;
       }

[Wladimir Palant, 2013/10/08 10:30:38]

I think that the logic here is still unnecessarily complicated, the outer if
block is unnecessary:

CComQIPtr<IHTMLDOMNode> pPrevSiblingNode = pEl;
long type = 0;
while (pPrevSiblingNode && type != 1)
{
  ... move up from pPrevSiblingNode ...
}

if (pPrevSiblingNode)
  hr = pPrevSiblingNode.QueryInterface();
else
  return false;

[Felix Dahlke, 2013/10/10 08:52:45]

Yes, that'd be better.

       break;
     }
     if (hr != S_OK)
       return false;
     return m_predecessor->IsMatchFilterElementHide(pDomPredecessor);
   }
 
   return true;
 }
 
@@ skipping 445 matching lines @@
   if (pos > 0 && domain.GetLength() + pos == subdomain.GetLength())
   {
     if (subdomain.GetAt(pos - 1) == '.')
     {
       return true;
     }
   }
 
   return false;
 }