windows-server-2003/admin/snapin/framewrk/dynamlnk.cpp

// DynamLnk.cpp : base class for DLLs which are loaded only when needed

#include "stdafx.h"
#include "DynamLnk.h"

DynamicDLL::DynamicDLL(LPCTSTR ptchLibraryName, LPCSTR* apchFunctionNames)
: m_hLibrary( (HMODULE)-1 ),
  m_apfFunctions( NULL ),
  m_ptchLibraryName( ptchLibraryName ),
  m_apchFunctionNames( apchFunctionNames ),
  m_nNumFunctions( 0 )
{
	ASSERT( !IsBadStringPtr(m_ptchLibraryName,MAX_PATH) );
	ASSERT( NULL != apchFunctionNames );
	for (LPCSTR pchFunctionName = *apchFunctionNames;
	     NULL != pchFunctionName;
		 pchFunctionName = *(++apchFunctionNames) )
	{
		m_nNumFunctions++;
		ASSERT( !IsBadStringPtrA(pchFunctionName,MAX_PATH) );
	}
}

DynamicDLL::~DynamicDLL()
{
	if (NULL != m_apfFunctions)
	{
		delete m_apfFunctions;
		m_apfFunctions = NULL;
	}
	if ((HMODULE)-1 != m_hLibrary && NULL != m_hLibrary)
	{
		VERIFY( ::FreeLibrary( m_hLibrary ) );
		m_hLibrary = NULL;
	}
}

BOOL DynamicDLL::LoadFunctionPointers()
{
	if ((HMODULE)-1 != m_hLibrary)
		return (NULL != m_hLibrary);

	m_hLibrary = ::LoadLibrary( m_ptchLibraryName );
	if (NULL == m_hLibrary)
	{
		// The library is not present
		return FALSE;
	}

	// let this throw an exception
	m_apfFunctions = new FARPROC[m_nNumFunctions];

	for (INT i = 0; i < m_nNumFunctions; i++)
	{
		m_apfFunctions[i] = ::GetProcAddress( m_hLibrary, m_apchFunctionNames[i] );
		if ( NULL == m_apfFunctions[i] )
		{
			// The library is present but does not have all of the entrypoints
			VERIFY( ::FreeLibrary( m_hLibrary ) );
			m_hLibrary = NULL;
			return FALSE;
		}
	}

	return TRUE;
}


FARPROC DynamicDLL::QueryFunctionPtr(INT i) const
{
	if ( 0 > i || m_nNumFunctions <= i || NULL == m_apfFunctions || NULL == m_apfFunctions[i] )
	{
		ASSERT( FALSE );
		return NULL;
	}
	return m_apfFunctions[i];
}