D12测试应用程序Device.cpp中两次用到CreateFile各是什么作用？(付源码)

两个CreateFile函数的作用是什么？我想应该是得到每个管道的句柄，那位大侠能说的具体点？函数是如何利用\"pipename\"找到相应的管道句柄的？急盼指教!!

char completeDeviceName[256] = \"\";  //generated from the GUID registered by the driver itself
HANDLE
OpenOneDevice (
    IN       HDEVINFO                    HardwareDeviceInfo,
    IN       PSP_INTERFACE_DEVICE_DATA   DeviceInfoData,
    IN                         char *devName
    )
{
    PSP_INTERFACE_DEVICE_DETAIL_DATA     functionClassDeviceData = NULL;
    ULONG                                predictedLength = 0;
    ULONG                                requiredLength = 0;
    HANDLE         hOut = INVALID_HANDLE_VALUE;

    SetupDiGetInterfaceDeviceDetail (
            HardwareDeviceInfo,
            DeviceInfoData,
            NULL, // probing so no output buffer yet
            0, // probing so output buffer length of zero
            &requiredLength,
            NULL); // not interested in the specific dev-node

    predictedLength = requiredLength;
    // sizeof (SP_FNCLASS_DEVICE_DATA) + 512;

    functionClassDeviceData = (PSP_INTERFACE_DEVICE_DETAIL_DATA)malloc (predictedLength);
    functionClassDeviceData->cbSize = sizeof (SP_INTERFACE_DEVICE_DETAIL_DATA);

    //
    // Retrieve the information from Plug and Play.
    //
    if (! SetupDiGetInterfaceDeviceDetail (
               HardwareDeviceInfo,
               DeviceInfoData,
               functionClassDeviceData,
               predictedLength,
               &requiredLength,
               NULL)) {
        return INVALID_HANDLE_VALUE;
    }

strcpy( devName,functionClassDeviceData->DevicePath) ;

    hOut = CreateFile (
                  functionClassDeviceData->DevicePath,
                  GENERIC_READ | GENERIC_WRITE,
                  FILE_SHARE_READ | FILE_SHARE_WRITE,
                  NULL, // no SECURITY_ATTRIBUTES structure
                  OPEN_EXISTING, // No special create flags
                  0, // No special attributes
                  NULL); // No template file

    if (INVALID_HANDLE_VALUE == hOut) {
    }

free(functionClassDeviceData);

return hOut;
}

HANDLE
OpenUsbDevice( LPGUID  pGuid, char *outNameBuf)

{
   ULONG NumberDevices;
   HANDLE hOut = INVALID_HANDLE_VALUE;
   HDEVINFO                 hardwareDeviceInfo;
   SP_INTERFACE_DEVICE_DATA deviceInfoData;
   ULONG                    i;
   BOOLEAN                  done;
   PUSB_DEVICE_DESCRIPTOR   usbDeviceInst;
   PUSB_DEVICE_DESCRIPTOR *UsbDevices = &usbDeviceInst;

   *UsbDevices = NULL;
   NumberDevices = 0;

   //
   // Open a handle to the plug and play dev node.
   // SetupDiGetClassDevs() returns a device information set that contains info on all
   // installed devices of a specified class.
   //
   hardwareDeviceInfo = SetupDiGetClassDevs (
                           pGuid,
                           NULL, // Define no enumerator (global)
                           NULL, // Define no
                           (DIGCF_PRESENT | // Only Devices present
                            DIGCF_INTERFACEDEVICE)); // Function class devices.

   //
   // Take a wild guess at the number of devices we have;
   // Be prepared to realloc and retry if there are more than we guessed
   //
   NumberDevices = 4;
   done = FALSE;
   deviceInfoData.cbSize = sizeof (SP_INTERFACE_DEVICE_DATA);

   i=0;
   while (!done)
   {
      NumberDevices *= 2;

      if (*UsbDevices)
 {
         *UsbDevices =
               (PUSB_DEVICE_DESCRIPTOR)realloc (*UsbDevices, (NumberDevices * sizeof (USB_DEVICE_DESCRIPTOR)));
      }
 else
 {
         *UsbDevices = (PUSB_DEVICE_DESCRIPTOR)calloc (NumberDevices, sizeof (USB_DEVICE_DESCRIPTOR));
      }

      if (NULL == *UsbDevices)
 {

         // SetupDiDestroyDeviceInfoList destroys a device information set
         // and frees all associated memory.

         SetupDiDestroyDeviceInfoList (hardwareDeviceInfo);
         return INVALID_HANDLE_VALUE;
      }

      usbDeviceInst = *UsbDevices + i;

      for (; i < NumberDevices; i++)
 {

         // SetupDiEnumDeviceInterfaces() returns information about device interfaces
         // exposed by one or more devices. Each call returns information about one interface;
         // the routine can be called repeatedly to get information about several interfaces
         // exposed by one or more devices.

         if (SetupDiEnumDeviceInterfaces (hardwareDeviceInfo,
                                         0, // We don\'t care about specific PDOs
pGuid,
                                         i,
                                         &deviceInfoData))
{

            hOut = OpenOneDevice (hardwareDeviceInfo, &deviceInfoData, outNameBuf);
if ( hOut != INVALID_HANDLE_VALUE )
{
               done = TRUE;
               break;
}
         }
else
{
            if (ERROR_NO_MORE_ITEMS == GetLastError())
{
               done = TRUE;
               break;
            }
         }
      }
   }

   NumberDevices = i;

   // SetupDiDestroyDeviceInfoList() destroys a device information set
   // and frees all associated memory.

   SetupDiDestroyDeviceInfoList (hardwareDeviceInfo);

   if (*UsbDevices)
  free(*UsbDevices);

   return hOut;
}

BOOL
GetUsbDeviceFileName( LPGUID  pGuid, char *outNameBuf)

{
HANDLE hDev = OpenUsbDevice( pGuid, outNameBuf );
if ( hDev != INVALID_HANDLE_VALUE )
{
CloseHandle( hDev );
return TRUE;
}
return FALSE;

}

HANDLE
open_dev()

{

HANDLE hDEV = OpenUsbDevice( (LPGUID)&GUID_CLASS_D12_BULK, completeDeviceName);

return hDEV;
}


HANDLE
open_file( char *pipename)

{

HANDLE h;

if ( !GetUsbDeviceFileName(
(LPGUID) &GUID_CLASS_D12_BULK,
completeDeviceName) )
{
return  INVALID_HANDLE_VALUE;
}

    strcat (completeDeviceName,
\"\\\\\"
);
    strcat (completeDeviceName,
pipename
);
h = CreateFile(completeDeviceName,
GENERIC_WRITE | GENERIC_READ,
FILE_SHARE_WRITE | FILE_SHARE_READ,
NULL,
OPEN_EXISTING,
//        FILE_FLAG_OVERLAPPED,
0,
NULL);

return h;
}


 

两个CreateFile函数的作用是什么？我想应该是得到每个管道的句柄，那位大侠能说的具体点？函数是如何利用"pipename"找到相应的管道句柄的？急盼指教!!
＊＊＊＊＊＊＊＊＊＊＊＊＊＊＊＊＊＊＊＊＊＊＊＊＊＊＊＊＊＊
我的理解：CreateFile仅仅是打开设备，管道句柄是在D12的设备驱动中StartDevice例程里获得的，保存在DeviceObject结构中，同时设备驱动在StartDevice例程中调用了D12_BuildPipeList，为每个被发现的管道依次取了名字（pipename），应用程序利用pipename指定管道，设备驱动根据这个pipename调出相应的管道句柄．