Hello

I have developed an NPAPI plugin for Firefox/Safari that I am now trying to get to work in Chrome without much success.

After some debugging I have found that in Chrome the plugin is getting stuck when I am creating an ActiveX control. The ActiveX control is loaded from the plugin DLL via the usual CoCreateInstance. However, this call never seems to return and Chrome locks up. The relevant call stack is given below. It appears that it is getting stuck in CDllHost::GetApartmentToken.

Anyone any ideas why?

Thanks
Mark

______________________________________________________

Call Stack:

Code:

 
ntdll.dll!_KiFastSystemCallRet@0() 
user32.dll!_NtUserMessageCall@28() + 0xc bytes 
user32.dll!_SendMessageW@16() + 0x49 bytes 
ole32.dll!CDllHost::GetApartmentToken() + 0x409e2 bytes 
ole32.dll!DoSTApartmentCreate() + 0x12 bytes 
ole32.dll!CClassCache::GetActivatorFromDllHost() + 0x556e5 bytes 
ole32.dll!CClassCache::GetOrCreateApartment() + 0x20 bytes 
ole32.dll!FindOrCreateApartment() + 0x46 bytes 
ole32.dll!CProcessActivator::GetApartmentActivator() + 0x89 bytes 
ole32.dll!CProcessActivator::CCICallback() + 0x17 bytes 
ole32.dll!CProcessActivator::AttemptActivation() + 0x2c bytes 
ole32.dll!CProcessActivator::ActivateByContext() + 0x46 bytes 
ole32.dll!CProcessActivator::CreateInstance() + 0x49 bytes 
ole32.dll!ActivationPropertiesIn::DelegateCreateInstance() + 0x4b bytes 
ole32.dll!CClientContextActivator::CreateInstance() + 0x8f bytes 
ole32.dll!ActivationPropertiesIn::DelegateCreateInstance() + 0x4b bytes 
ole32.dll!ICoCreateInstanceEx() + 0x10b4b bytes 
ole32.dll!CComActivator::DoCreateInstance() + 0x28 bytes 
ole32.dll!_CoCreateInstanceEx@24() + 0x1e bytes 
ole32.dll!_CoCreateInstance@20() + 0x34 bytes 
npagraph.dll!ATL::CreateNormalizedObject(const wchar_t * lpszTricsData=0x10b9a164, const _GUID & riid={...}, void * * ppvObj=0x0127f540, bool & bWasHTML=false, wchar_t * bstrLicKey=0x00000000) Line 135 + 0x16 bytes C++
npagraph.dll!ATL::CAxHostWindow::CreateControlLicEx(const wchar_t * lpszTricsData=0x10b9a164, HWND__ * hWnd=0x00190eec, IStream * pStream=0x00000000, IUnknown * * ppUnk=0x0127f540, const _GUID & iidAdvise={...}, IUnknown * punkSink=0x00000000, wchar_t * bstrLic=0x00000000) Line 844 + 0x1a bytes C++
npagraph.dll!ATL::CAxHostWindow::CreateControlEx(const wchar_t * lpszTricsData=0x10b9a164, HWND__ * hWnd=0x00190eec, IStream * pStream=0x00000000, IUnknown * * ppUnk=0x0127f540, const _GUID & iidAdvise={...}, IUnknown * punkSink=0x00000000) Line 732 C++
npagraph.dll!ATL::CAxWindowT<ATL::CWindow>::CreateControlEx(const wchar_t * lpszName=0x10b9a164, IStream * pStream=0x00000000, IUnknown * * ppUnkContainer=0x00000000, IUnknown * * ppUnkControl=0x0127f5ec, const _GUID & iidSink={...}, IUnknown * punkSink=0x00000000) Line 2036 + 0x38 bytes C++
npagraph.dll!agraphfirefoxplugin::CreateToolbars(HWND__ * parenthwnd=0x00190ff2) Line 650 + 0x27 bytes C++
npagraph.dll!agraphfirefoxplugin::CreateControlWindow(OWL::TRect & pluginrect={...}) Line 571 C++
npagraph.dll!agraphfirefoxplugin::init(_NPWindow * aWindow=0x0101b738) Line 384 C++
npagraph.dll!NPP_SetWindow(_NPP * instance=0x00fb0060, _NPWindow * pNPWindow=0x0101b738) Line 112 + 0x10 bytes C++
chrome.dll!NPAPI::PluginInstance::NPP_SetWindow(_NPWindow * window=0x0101b738) Line 233 + 0x9 bytes C++
chrome.dll!WebPluginDelegateImpl::WindowedSetWindow() Line 794 C++
chrome.dll!WebPluginDelegateImpl::UpdateGeometry(const gfx::Rect & window_rect={...}, const gfx::Rect & clip_rect={...}) Line 388 + 0x1c bytes C++

Anyone got any ideas??

Thanks
Mark

I don't know if this could be of any help but this extension also uses npapi plugin -> http://www.chromeextensions.org/utilities/switch-proxy/ so maybe some reverse engineering or contacting developer

OK thanks - I'll have a look.

Basically though my plugin is working. It is just when I try to create an ActiveX control, using CoCreateInstance, from within the plugin DLL that Chrome locks up. If I take out the ActiveX control creation from the code, then the plugin runs successfully. Therefore I am deducing that there is something odd about creating an ActiveX/COM object within the Chrome plugin environment.

Haven't a clue what though!

Hi markh, you mentioned you already developed the NPAPI plugin for Firefox and Safari. Is it based on this code that you now have problems with? Are you sure the Firefox and Safari versions also create an ActiveX object?

So far, IE is the only browser that supports ActiveX. Are you positive that a plugin that uses an ActiveX object works for Firefox and Safari?

As far as I know, requiring ActiveX will definitely fail for all of Firefox and Safari and Chrome.

The plugin works perfectly in Firefox and Safari and I am now trying to use exactly the same plugin in Chrome.

The plugin itself is a standard NPAPI plugin DLL and not an ActiveX control. I realize that ActiveX controls themselves are not supported by Netscape type browsers. The ActiveX control is created from within the NPAPI DLL and just provides part of of the UI for the plugin.

As I said, the ActiveX creation works fine in Firefox and Safari. It is just Chrome that seems to have a problem. If I remove the UI element in the plugin code, and thus don't create the ActiveX control, then the rest of the plugin functions successfully in Chrome.

Any ideas?

ActiveX is not supported in Chrome

Judging by the callstack, you likely have some confusion over OLE apartment model threading (confusion can happen easily in this arena :-)). First off, ensure the COM objects you are using have been designated for the correct threading model (here's an example where that was the problem: http://blogs.msdn.com/asiatech/archi...d-handler.aspx).


Also, there is something suspicious in that it looks like NPP_SetWindow in this case is not being called for initialization but for a geometry update. Be aware that NPP_SetWindow is called for events like resize, not just initialization, so you may be re-initializing your control at an inappropriate time.

Thanks for the help. It did indeed turn out to be a threading model issue. When I added the following line into the manifest file for the ActiveX control, it solved the problem:

threadingModel="Apartment"

The plugin now functions 100% in Chrome.