C++ / Share variable or send data from unmanaged to managed in the same DLL

Question

I Have a mixed mode DLL containing a unmanaged part (DllMain) and a managed C++ part.

I calculate some folders in DllMain and I want to share/send data to the managed part when it is called.

I load DLL using LoadLibrary from another C++ program.

How can I share data or send data from DllMain to the managed part ?

I have to share/send some char*.

Thanks

Answer 1

You need to export a native function from the managed DLL, which native DLL can call upon. Or, you can have an interface (C++ interface), powered by a CreateThisObject or similar, which will instantiate the derived-class (of interface). This interface, as well as the creation-function will be given by managed DLL, and native DLL will simply use it as normal C++ class.

Kind-of pseudo-code is presented below

// Export function only
EXPORT
int DoSomethingInManagedDLL(args);

// Export hidden class, through an interface
class IDLLHelper
{
   virtual void DoSomething() = 0;
};

EXPORT IDLLHelper* CreateDLLHelper();

// Some class, known only to managed DLL
// This class, as well as above' interface is native

class DLLHelperImpl : public IDLLHelper
{
   void DoSomething()
   {
    // actual code
   }
};