rfid-credential-provider/Provider/RfidCredentialProvider/Dll.cpp

//
// THIS CODE AND INFORMATION IS PROVIDED "AS IS" WITHOUT WARRANTY OF
// ANY KIND, EITHER EXPRESSED OR IMPLIED, INCLUDING BUT NOT LIMITED TO
// THE IMPLIED WARRANTIES OF MERCHANTABILITY AND/OR FITNESS FOR A
// PARTICULAR PURPOSE.
//
// Copyright (c) 2006 Microsoft Corporation. All rights reserved.
//
// Standard dll required functions and class factory implementation.

#include <windows.h>
#include "Dll.h"
#include "guid.h"

static LONG g_cRef = 0;   // global dll reference count

// IClassFactory ///////////////////////////////////////////////////////////////////////

extern HRESULT RfidProvider_CreateInstance(REFIID riid, void** ppv);

HINSTANCE g_hinst = nullptr;   // global dll hinstance

class CClassFactory : public IClassFactory
{
public:
	// IUnknown
	STDMETHOD_(ULONG, AddRef)()
	{
		return _cRef++;
	}

	STDMETHOD_(ULONG, Release)()
	{
		LONG cRef = _cRef--;
		if (!cRef)
		{
			delete this;
		}
		return cRef;
	}

	STDMETHOD(QueryInterface)(REFIID riid, void** ppv)
	{
		HRESULT hr;
		if (ppv != NULL)
		{
			if (IID_IClassFactory == riid || IID_IUnknown == riid)
			{
				*ppv = static_cast<IUnknown*>(this);
				reinterpret_cast<IUnknown*>(*ppv)->AddRef();
				hr = S_OK;
			}
			else
			{
				*ppv = NULL;
				hr = E_NOINTERFACE;
			}
		}
		else
		{
			hr = E_INVALIDARG;
		}
		return hr;
	}

	// IClassFactory
	STDMETHOD(CreateInstance)(IUnknown* pUnkOuter, REFIID riid, void** ppv)
	{
		HRESULT hr;
		if (!pUnkOuter)
		{
			hr = RfidProvider_CreateInstance(riid, ppv);
		}
		else
		{
			hr = CLASS_E_NOAGGREGATION;
		}
		return hr;
	}

	STDMETHOD(LockServer)(BOOL bLock)
	{
		if (bLock)
		{
			DllAddRef();
		}
		else
		{
			DllRelease();
		}
		return S_OK;
	}

private:
	CClassFactory() : _cRef(1) {}
	~CClassFactory() {}

private:
	LONG _cRef;
	friend HRESULT CClassFactory_CreateInstance(REFCLSID rclsid, REFIID riid, void** ppv);
};

HRESULT CClassFactory_CreateInstance(REFCLSID rclsid, REFIID riid, void** ppv)
{
	HRESULT hr;
	if (CLSID_RfidProvider == rclsid)
	{
		CClassFactory* pcf = new CClassFactory;
		if (pcf)
		{
			hr = pcf->QueryInterface(riid, ppv);
			pcf->Release();
		}
		else
		{
			hr = E_OUTOFMEMORY;
		}
	}
	else
	{
		hr = CLASS_E_CLASSNOTAVAILABLE;
	}
	return hr;
}

// DLL Functions ///////////////////////////////////////////////////////////////////////

BOOL WINAPI DllMain(
	HINSTANCE hinstDll,
	DWORD dwReason,
	LPVOID pReserved
)
{
	UNREFERENCED_PARAMETER(pReserved);
	switch (dwReason)
	{
	case DLL_PROCESS_ATTACH:
		DisableThreadLibraryCalls(hinstDll);
		break;
	case DLL_PROCESS_DETACH:
	case DLL_THREAD_ATTACH:
	case DLL_THREAD_DETACH:
		break;
	}
	g_hinst = hinstDll;
	return TRUE;
}

void DllAddRef()
{
	InterlockedIncrement(&g_cRef);
}

void DllRelease()
{
	InterlockedDecrement(&g_cRef);
}

// DLL entry point.
STDAPI DllCanUnloadNow()
{
	HRESULT hr;
	if (g_cRef > 0)
	{
		hr = S_FALSE;   // cocreated objects still exist, don't unload
	}
	else
	{
		hr = S_OK;      // refcount is zero, ok to unload
	}
	return hr;
}

// DLL entry point.
STDAPI DllGetClassObject(REFCLSID rclsid, REFIID riid, void** ppv)
{
	return CClassFactory_CreateInstance(rclsid, riid, ppv);
}