How to Determine the Type of Handle Retrieved from OpenPrinter

• Microsoft Win32 Application Programming Interface (API) included with:

      - Microsoft Windows NT versions 3.1, 3.5, and 3.51
      - Microsoft Windows 95 version 4.0
  

OpenPrinter returns a valid handle when a printer name or a server name is passed to it. Sometimes it may be necessary to determine if the returned handle is a handle to a printer because some Win32 spooler functions only accept printer handles and will fail on server handles. The following code determines if a handle is a printer handle:

BOOL IsPrinterHandle( HANDLE hPrinter) {

    DWORD       cbNeeded;
    DWORD       Error;
    BOOL        bRet = FALSE;
    LPPRINTER_INFO_2 pPrinter;
    DWORD       cbBuf;
    HANDLE      hMem = NULL;

    if( !GetPrinter(hPrinter, 2, (LPBYTE)NULL, cbBuf, &cbNeeded ))
    {
        Error = GetLastError( );

        if( Error == ERROR_INSUFFICIENT_BUFFER )
        {
            hMem = GlobalAlloc(GHND, cbNeeded);
            if (!hMem) return bRet;
            pPrinter = (LPPRINTER_INFO_2)GlobalLock(hMem);
            cbBuf = cbNeeded;
            if(GetPrinter(hPrinter, 2, (LPBYTE)pPrinter, cbBuf, &cbNeeded))
            {
                bRet = TRUE;
                GlobalUnlock(hMem);
                GlobalFree(hMem);
            }
            else SetLastError( ERROR_INVALID_PRINTER_NAME );
        }
        else if( Error == ERROR_INVALID_HANDLE )
        {
            SetLastError( ERROR_INVALID_PRINTER_NAME );
        }
    }
    return bRet;