How to copy an EFS file with C++ CLI?

///////////////////////////////////////////////// HEADER //////////////////////////////////
// EFSClassTest.h
 
#pragma once
 
using namespace System;
using namespace System::IO;
 
namespace EFSClassTest 
{
	public ref class EFSRaw
	{
	public:
		EFSRaw();
 
		bool Backup(String ^theSourceFileName, FileStream ^theTarget);
		bool Restore(FileStream ^theSource, String ^theTargetFileName);
		
	private:
		static  IntPtr ^invalidHandleValue = gcnew IntPtr(-1);
		literal UInt32 BUFFER_SIZE = 4096;
 
		array<Byte> ^buffdata;
		FileStream ^stream;
		UInt64 bytesWritten;
 
		delegate Int32 ImportCallBack(IntPtr pbdata, IntPtr pvCallbackContext, int %ulLength); 
		delegate Int32 ExportCallBack(IntPtr pbdata, IntPtr pvCallbackContext, int ulLength); 
		
		Int32 ReadCallBack(IntPtr pbdata, IntPtr pvCallbackContext, int ulLength);
		Int32 WriteCallBack(IntPtr pbdata, IntPtr pvCallbackContext, int %ulLength);
	};
}
////////////////////////////////////////////////////////////////////////////
/////////////////////////////////////// CPP ////////////////////////////////
////////////////////////////////////////////////////////////////////////////
#include "stdafx.h"
#include <windows.h>
#include <vcclr.h>  //for PtrToStringChars
#include "EFSClassTest.h"
 
using namespace System::Runtime::InteropServices;
 
namespace EFSClassTest
{
	EFSRaw::EFSRaw() 
	{
		buffdata = gcnew array<Byte>(BUFFER_SIZE);
		stream = nullptr;
		bytesWritten = 0;
	}
 
	/// <summary>
	/// Read an encrypted file and write its data to a stream.
	/// </summary>
	/// <param name="source">encrypted file to back up</param>
	/// <param name="destination">stream to write data to</param>
	/// <returns>true if successful</returns>
	bool EFSRaw::Backup(String ^theSourceFileName, FileStream ^theTarget)
	{
		bool status = false;
 
		PVOID pvContext = NULL;
		stream = theTarget;
		bytesWritten = 0;
 
		pin_ptr<const wchar_t> sourceFileName = PtrToStringChars(theSourceFileName);
 
		if (OpenEncryptedFileRaw((LPWSTR) sourceFileName, 0, &pvContext) != ERROR_SUCCESS)
		{
			status = false;
		}
		else
		{
			ExportCallBack ^ecb = gcnew ExportCallBack(this, &EFSRaw::ReadCallBack);
			pin_ptr<ExportCallBack^> tmp = &ecb;
			PFE_EXPORT_FUNC pEcb = (PFE_EXPORT_FUNC) Marshal::GetFunctionPointerForDelegate(ecb).ToPointer();
 
			status = (ReadEncryptedFileRaw(pEcb, nullptr, pvContext) == ERROR_SUCCESS);
 
			CloseEncryptedFileRaw(pvContext);
			theTarget->Flush();
		}
 
		return status;
	}
 
	/// <summary>
	/// Callback function called by ReadEncryptedFileRaw().
	/// </summary>
	/// <param name="pbdata">pointer to data read</param>
	/// <param name="pvCallbackContext">parameter</param>
	/// <param name="ulLength">length of data read</param>
	/// <returns>ERROR_SUCCESS</returns>
	Int32 EFSRaw::ReadCallBack(IntPtr pbdata, IntPtr pvCallbackContext, int ulLength)
	{
		Int32 result = ERROR_SUCCESS;
 
		if (ulLength > buffdata->Length)
		{
			buffdata = gcnew array<Byte>(ulLength);
		}
		Marshal::Copy(pbdata, buffdata, 0, ulLength);
 
		stream->Write(buffdata, 0, ulLength);
		bytesWritten += ulLength;
 
		return result;
	}
 
	/// <summary>
	/// Restore an encrypted file with data read from a stream.
	/// </summary>
	/// <param name="source">stream to read from</param>
	/// <param name="destination">name of encrypted file to create</param>
	/// <returns>true if successful</returns>
	bool EFSRaw::Restore(FileStream ^theSource, String ^theTargetFileName)
	{
		bool status = false;
		PVOID pvContext = NULL;
		stream = theSource;
		bytesWritten = 0;
 
		pin_ptr<const wchar_t> targetFileName = PtrToStringChars(theTargetFileName);
		if (OpenEncryptedFileRaw((LPWSTR) targetFileName, CREATE_FOR_IMPORT, &pvContext) != ERROR_SUCCESS)
		{
			status = false;
		}
		else
		{
			ImportCallBack ^icb = gcnew ImportCallBack(this, &EFSRaw::WriteCallBack);
			pin_ptr<ImportCallBack^> tmp = &icb;
			PFE_IMPORT_FUNC pIcb = (PFE_IMPORT_FUNC) Marshal::GetFunctionPointerForDelegate(icb).ToPointer();
 
			status = (WriteEncryptedFileRaw(pIcb, nullptr, pvContext) == ERROR_SUCCESS);
 
			CloseEncryptedFileRaw(pvContext);
		}
		return status;
	}
 
 
	/// <summary>
	/// Callback function called by WriteEncryptedFileRaw().
	/// </summary>
	/// <param name="pbdata">pointer to memory</param>
	/// <param name="pvCallbackContext">parameter</param>
	/// <param name="ulLength">memory buffer size</param>
	/// <returns>ERROR_SUCCESS</returns>
	Int32 EFSRaw::WriteCallBack(IntPtr pbdata, IntPtr pvCallbackContext, int %ulLength)
	{
		Int32 result = ERROR_SUCCESS;
 
		Int32 dataToWrite = Math::Min((int) buffdata->Length, ulLength);
 
		// read stream into buffer
		Int32 bytesRead = stream->Read(buffdata, 0, dataToWrite);
 
		// copy buffer
		Marshal::Copy(buffdata, 0, pbdata, bytesRead);
 
		ulLength = bytesRead;
		bytesWritten += bytesRead;
 
		return result;
	}
}

                                              

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