Lingering COM Objects Caused by ActiveX Control Event Handlers

// DataInfo.cpp : Implementation of CDataInfo

#include "stdafx.h"
#include "DataInfo.h"

// CDataInfo

// internal function to flush the data and close up the file 
void CDataInfo::Close(void)
{
	// update and close the file if open 
	if (m_hFile)
	{
		// write out our current data 
		DWORD written = 0; 
		WriteFile(m_hFile, m_bstrData.GetBSTR(), sizeof(wchar_t) * m_bstrData.length(), &written, NULL); 

		// close the file 
		::CloseHandle(m_hFile); 
	}
	m_hFile = NULL; 
}

// initialize to specify the output file 
STDMETHODIMP CDataInfo::Initialize(BSTR bstrFileName)
{
	// if already open, return error 
	if (m_hFile != NULL)
		return(E_FAIL); 

	// attempt to open the file for reading and writing (clear any existing contents for simplicity)
	m_hFile = ::CreateFile(bstrFileName, FILE_READ_DATA | FILE_WRITE_DATA, 0, NULL, CREATE_ALWAYS, FILE_ATTRIBUTE_NORMAL, NULL); 
	if (m_hFile == INVALID_HANDLE_VALUE) 
	{ 
		m_hFile = NULL; 
		return(HRESULT_FROM_WIN32(GetLastError())); 
	}

	// ideally we would refresh our internal buffer with the previous contents of the file here, 
	// but for simplicity, start with an empty buffer...

	// success
	return S_OK;
}

// update our datasource with new data 
STDMETHODIMP CDataInfo::put_DataContents(BSTR newVal)
{
	HRESULT hRes = S_OK; 

	// if they didn't initialize, then return error 
	if (!m_hFile) 
		return(E_FAIL); 
	
	// copy the input data 
	try
	{
		m_bstrData = newVal; 
	}
	catch (_com_error &e)
	{
		hRes = e.Error(); 
	}

	// status
	return(hRes);
}

// get the current contents of the datasource
STDMETHODIMP CDataInfo::get_DataContents(BSTR* pVal)
{
	HRESULT hRes = S_OK; 

	// if they didn't initialize, then return error 
	if (!m_hFile) 
		return(E_FAIL); 

	// return a copy of the current data 
	try
	{
		*pVal = m_bstrData.copy(); 
	}
	catch (_com_error &e)
	{
		hRes = e.Error(); 
	}

	// status
	return(hRes);
}