Using Pragmas to Create a Proxy DLL

#include <windows.h>
#include <advapi32_fwd.h>
#pragma pack(1)

static HINSTANCE hLThis = 0;
static HINSTANCE hADVAPI32 = 0;
static TCHAR prtBuf[0x1000];
static DWORD dwWidth, dwHeight, dwFog, dwMIP, dwTexture, dwTrans;

//! The real API functions.
static LONG( APIENTRY *ADVAPI32_RegQueryValueExA )(
    HKEY hKey,
    LPCTSTR lpValueName,
    LPDWORD lpReserved,
    LPDWORD lpType,
    LPBYTE lpData,
    LPDWORD lpcbData
);
static LONG( APIENTRY *ADVAPI32_RegSetValueExA )(
    HKEY hKey,
    LPCTSTR lpValueName,
    DWORD Reserved,
    DWORD dwType,
    const BYTE* lpData,
    DWORD cbData
);

//! Hooked functions.
extern "C" LONG APIENTRY HookedRegQueryValueExA(
        HKEY hKey,
        LPCTSTR lpValueName,
        LPDWORD lpReserved,
        LPDWORD lpType,
        LPBYTE lpData,
        LPDWORD lpcbData
    )
{
    LONG retVal = ADVAPI32_RegQueryValueExA( hKey, lpValueName, lpReserved, lpType, lpData, lpcbData );

    if( !lstrcmpi( lpValueName, "Display Height" ) )
    {
        *( DWORD * )lpData = dwHeight;
#ifdef _DEBUG
        wsprintf( prtBuf, "Faking display height to %d.\n", dwHeight );
        OutputDebugString( prtBuf );
#endif
    }
    else if( !lstrcmpi( lpValueName, "Display Width" ) )
    {
        *( DWORD * )lpData = dwWidth;
#ifdef _DEBUG
        wsprintf( prtBuf, "Faking display width to %d.\n", dwWidth );
        OutputDebugString( prtBuf );
#endif
    }
    else if( !lstrcmpi( lpValueName, "Fog" ) )
    {
        *( DWORD * )lpData = dwWidth;
#ifdef _DEBUG
        wsprintf( prtBuf, "Faking fog to %d.\n", dwFog );
        OutputDebugString( prtBuf );
#endif
    }
    else if( !lstrcmpi( lpValueName, "MIP Mapping" ) )
    {
        *( DWORD * )lpData = dwWidth;
#ifdef _DEBUG
        wsprintf( prtBuf, "Faking MIP mapping to %d.\n", dwMIP );
        OutputDebugString( prtBuf );
#endif
    }
    else if( !lstrcmpi( lpValueName, "Texture Filtering" ) )
    {
        *( DWORD * )lpData = dwWidth;
#ifdef _DEBUG
        wsprintf( prtBuf, "Faking texture filtering to %d.\n", dwTexture );
        OutputDebugString( prtBuf );
#endif
    }
    else if( !lstrcmpi( lpValueName, "Translucency" ) )
    {
        *( DWORD * )lpData = dwWidth;
#ifdef _DEBUG
        wsprintf( prtBuf, "Faking translucency to %d.\n", dwTrans );
        OutputDebugString( prtBuf );
#endif
    }
    return retVal;
}

extern "C" LONG APIENTRY HookedRegSetValueExA(
        HKEY hKey,
        LPCTSTR lpValueName,
        DWORD Reserved,
        DWORD dwType,
        const BYTE* lpData,
        DWORD cbData
    )
{
    LONG retVal = ADVAPI32_RegSetValueExA( hKey, lpValueName, Reserved, dwType, lpData, cbData );
#ifdef _DEBUG
    wsprintf( prtBuf, "Set value for '%s'.\n", lpValueName );
    OutputDebugString( prtBuf );
    wsprintf( prtBuf, "New value '%s'.\n", lpData );
    OutputDebugString( prtBuf );
#endif
    return retVal;
}

//! Get resolutions.
BOOL GetReso( DWORD *width, DWORD *height )
{
    HKEY hKey;
    if( ERROR_SUCCESS == RegOpenKeyEx( HKEY_CURRENT_USER,
        "SOFTWARE\\MechProxy", 0, KEY_READ, &hKey ) )
    {
        //! Read values from registry.
        DWORD flag, type, count = 4;
#define GET_REG_DWORD( str, var ) \
flag = 0;\
RegQueryValueEx( hKey, str, NULL, &type, (LPBYTE)&var, &count )
        GET_REG_DWORD( "Display Width", dwWidth );
        GET_REG_DWORD( "Display Height", dwHeight );
        GET_REG_DWORD( "Fog", dwFog );
        GET_REG_DWORD( "MIP Mapping", dwMIP );
        GET_REG_DWORD( "Texture Filtering", dwTexture );
        GET_REG_DWORD( "Translucency", dwTrans );

        //! Close key.
        RegCloseKey( hKey );
        return TRUE;
    }
    return(FALSE);
}

//! Attach or detach this proxy.
BOOL WINAPI DllMain( HINSTANCE hInst,DWORD reason,LPVOID )
{
    if( reason == DLL_PROCESS_ATTACH )
    {
        OutputDebugString( "ADVAPI32 Proxy DLL starting.\n" );
        hLThis = hInst;
        hADVAPI32 = LoadLibrary( "advapi32" );
        if( !hADVAPI32 )
        {
            return FALSE;
        }
        *( void ** )&ADVAPI32_RegQueryValueExA =( void * )GetProcAddress( hADVAPI32, "RegQueryValueExA" );
        *( void ** )&ADVAPI32_RegSetValueExA =( void * )GetProcAddress( hADVAPI32, "RegSetValueExA" );

        //! Query for the resolution to use.
        if( FALSE == GetReso( &dwWidth, &dwHeight ) )
        {
            dwHeight =( DWORD )-1;
            dwWidth =( DWORD )-1;
        }
    }
    else if( reason == DLL_PROCESS_DETACH )
    {
        FreeLibrary( hADVAPI32 );
        OutputDebugString( "ADVAPI32 Proxy DLL signing off.\n" );
    }
    return TRUE;
}
//! End of file.