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// 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) Microsoft Corporation. All rights reserved
//
// File Name:
//
// UnknownBase.h
//
// Abstract:
//
// IUnknown implementation common to filter components derived from
// IUnknown.
//
#pragma once
namespace xpsrasfilter
{
template <class Interface>
class UnknownBase : public Interface
{
public:
UnknownBase() : m_cRef(1) { }
virtual ~UnknownBase() { };
//
//Routine Name:
//
// UnknownBase::QueryInterface
//
//Routine Description:
//
// Implements IUnknown QueryInterface.
//
//Arguments:
//
// riid - id of the interface
// ppv - void pointer to the requested interface
//
//Return Value:
//
// HRESULT
// S_OK - On success
// E_NOINTERFACE - Invalid interface
//
_Must_inspect_result_
HRESULT STDMETHODCALLTYPE
QueryInterface(
_In_ REFIID riid,
_Outptr_ PVOID *ppv
)
{
HRESULT hr = S_OK;
if (ppv == NULL)
{
WPP_LOG_ON_FAILED_HRESULT(E_POINTER);
return E_POINTER;
}
if (riid == IID_IUnknown)
{
*ppv = static_cast<IUnknown *>(this);
}
else if (riid == __uuidof(Interface))
{
*ppv = static_cast<Interface *>(this);
}
else
{
*ppv = NULL;
WPP_LOG_ON_FAILED_HRESULT(
hr = E_NOINTERFACE
);
}
if (SUCCEEDED(hr))
{
AddRef();
}
return hr;
}
//
//Routine Name:
//
// UnknownBase::AddRef
//
//Routine Description:
//
// Implements IUnknown reference count increment
// on the current interface.
//
//Arguments:
//
// None
//
//Return Value:
//
// ULONG
// New reference count
//
ULONG STDMETHODCALLTYPE
AddRef()
{
return ::InterlockedIncrement(&m_cRef);
}
//
//Routine Name:
//
// UnknownBase::Release
//
//Routine Description:
//
// Implements IUnknown reference count decrement
// on the current interface.
//
//Arguments:
//
// None
//
//Return Value:
//
// ULONG
// New reference count
//
//Note:
//
// The drv_at annotation tells Prefast to consider this object's memory
// freed after Release has been called.
//
_At_(this, __drv_freesMem(object))
ULONG STDMETHODCALLTYPE
Release()
{
ULONG cRef = ::InterlockedDecrement(&m_cRef);
if (0 == cRef)
{
delete this;
}
return cRef;
}
private:
volatile ULONG m_cRef; // interface reference count
};
} // namespace xpsrasfilter
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