Interface Handler Plug-in

You can write an interface handler plug-in to provide programmatic user-mode access to a driver-specific property set that is exposed by a KS minidriver. First, register your object as described in Registering KS Proxy Plug-ins.

Your interface plug-in class could derive from CUnknown:


class CMyPluginInterface : public CUnknown 
{
public:
    // creation method
    static CUnknown* CALLBACK CreateInstance( LPUNKNOWN piOuterUnknown, HRESULT* phResult );
private:
 CMyPluginInterface( IKsPropertySet* piKsPropertySet );
    IKsPropertySet* m_piKsPropertySet;
};

The interface plug-in is a vendor-supplied COM interface that aggregates with the MS-provided KS proxy at create time.

Specifically, the CreateInstance method of the plug-in receives a pointer to KS proxy as an outer unknown.

You can then query this outer object for a pointer to the MS-provided IKsPropertySet interface:


hResult = piOuterUnknown->QueryInterface(
                __uuidof( piKsPropertySet ),
                 &piKsPropertySet );

Then, from CreateInstance, invoke the constructor of your interface to create an instance of your interface handler object.

Provide the pointer to IKsPropertySet as a parameter in the invocation of the constructor. The constructor then retains the pointer to iKsPropertySet as the m_piKsPropertySet member in the previous declaration.

Now you can implement Get and Set methods in your class that call IKsPropertySet::Get and IKsPropertySet::Set respectively to manipulate properties that are exposed by the driver.

Alternatively, you can query the outer unknown for a pointer to its IKsObject interface. Then call IKsObject::KsGetObjectHandle to obtain a file handle. Now you manipulate device properties by calling KsSynchronousIoControlDevice with this file handle.

 

 

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