用这个函数试试

//GetDeviceViaInterface:Open a handle via a device interface

HANDLE GetDeviceViaInterface( GUID* pGuid, DWORD instance)

{

// Get handle to relevant device information set

HDEVINFO info = SetupDiGetClassDevs(pGuid, NULL, NULL, DIGCF_PRESENT | DIGCF_INTERFACEDEVICE);

if(info==INVALID_HANDLE_VALUE)

{

printf(\"No HDEVINFO available for this GUID\\n\");

return NULL;

}

// Get interface data for the requested instance

SP_INTERFACE_DEVICE_DATA ifdata;

ifdata.cbSize = sizeof(ifdata);

if(!SetupDiEnumDeviceInterfaces(info, NULL, pGuid, instance, &ifdata))

{

printf(\"No SP_INTERFACE_DEVICE_DATA available for this GUID instance\\n\");

SetupDiDestroyDeviceInfoList(info);

return NULL;

}

// Get size of symbolic link name

DWORD ReqLen;

SetupDiGetDeviceInterfaceDetail(info, &ifdata, NULL, 0, &ReqLen, NULL);

PSP_INTERFACE_DEVICE_DETAIL_DATA ifDetail = (PSP_INTERFACE_DEVICE_DETAIL_DATA)(new char[ReqLen]);

if( ifDetail==NULL)

{

return NULL;

}

// Get symbolic link name

ifDetail->cbSize = sizeof(SP_INTERFACE_DEVICE_DETAIL_DATA);

if( !SetupDiGetDeviceInterfaceDetail(info, &ifdata, ifDetail, ReqLen, NULL, NULL))

{

SetupDiDestroyDeviceInfoList(info);

delete ifDetail;

return NULL;

}

printf(\"Symbolic link is %s\\n\",ifDetail->DevicePath);

// Open file and pipe

HANDLE rv = CreateFile(ifDetail->DevicePath,

GENERIC_READ | GENERIC_WRITE,

FILE_SHARE_READ | FILE_SHARE_WRITE,

NULL, OPEN_EXISTING, FILE_ATTRIBUTE_NORMAL, NULL);

if( rv==INVALID_HANDLE_VALUE) rv = NULL;

delete ifDetail;

SetupDiDestroyDeviceInfoList(info);

return rv;

}