www.pudn.com > windows2000XP_WDM_DeviceDriverDevelopment_WuAnHe_C > OpenByIntf.cpp


// OpenByIntf.cpp - open device by device interface
// Copyright (c) 1998 Compuware Corporation

#define NOCRYPT // prevent attempt to include missing files
#define _INC_EXCPT // prevent excpt.h from being included

#include <stdlib.h>
#include <windows.h>
#include <winioctl.h>
#include <devintf.h> // DriverWorks

// OpenByInterface
//
// Opens the nth device found with the given interface class

HANDLE OpenByInterface(
GUID* pClassGuid, // points to the GUID that identifies the interface class
DWORD instance, // specifies which instance of the enumerated devices to open
PDWORD pError // address of variable to receive error status
)
{
HANDLE hDev;
CDeviceInterfaceClass DevClass(pClassGuid, pError);

if (*pError != ERROR_SUCCESS)
return INVALID_HANDLE_VALUE;

CDeviceInterface DevInterface(&amt;DevClass, instance, pError);

if (*pError != ERROR_SUCCESS)
return INVALID_HANDLE_VALUE;

hDev = CreateFile(
DevInterface.DevicePath(),
GENERIC_READ | GENERIC_WRITE,
FILE_SHARE_READ | FILE_SHARE_WRITE,
NULL,
OPEN_EXISTING,
FILE_ATTRIBUTE_NORMAL,
NULL
);

if (hDev == INVALID_HANDLE_VALUE)
*pError = GetLastError();

return hDev;
}