getting the device path / device handle of a specific device

Hi,
I'm trying to write an application which returns me a handle to a
device in C#. I already got most of the information needed for this
purpose, like the DeviceInfoSet (as IntPtr), the SP_DEVINFO_DATA
struct, the device name, ... But the final step, calling
SetupDiEnumDeviceInterfaces() to retrieve the SP_DEVICE_INTERFACE_DATA
struct fails. Extraction from my code:


//get device info set for the device class
_deviceInfoSet = SetupDiGetClassDevs(ref _guids[0], 0,
IntPtr.Zero, DIGCF_PRESENT);
if (_deviceInfoSet.ToInt32() == -1)
if (!res) { //device information is unavailable:
_deviceName = new StringBuilder("");
_errorcode = -3; return;
}

//_deviceInfoData.cbSize = (uint)
Marshal.SizeOf(_deviceInfoData);
_deviceInfoData.cbSize = 28;
_deviceInfoData.DevInst = 0;
_deviceInfoData.ClassGuid = System.Guid.Empty;
_deviceInfoData.Reserved = 0;

res = SetupDiEnumDeviceInfo(_deviceInfoSet, _deviceIndex,
_deviceInfoData);
if (!res) { //no such device:
SetupDiDestroyDeviceInfoList(_deviceInfoSet);
_deviceName = new StringBuilder("");
_errorcode = -1; return;
}

// code for get the device name by calling
SetupDiGetDeviceRegistryProperty() ....


/* ok till here */


SP_DEVICE_INTERFACE_DETAIL_DATA diDetail = new
SP_DEVICE_INTERFACE_DETAIL_DATA();
//diDetail.cbSize = (uint) Marshal.SizeOf(diDetail);
if (IntPtr.Size == 8)
diDetail.cbSize = 8;
else
diDetail.cbSize = 5;
uint size1 = 0;

// get Buffer Size
bool check =
SetupDiGetDeviceInterfaceDetail(_deviceInfoSet, ref _deviceInfoData,
IntPtr.Zero, 0, out size1, IntPtr.Zero);
check =
SetupDiGetDeviceInterfaceDetail(_deviceInfoSet, ref _deviceInfoData,
ref diDetail, size1, out size1, IntPtr.Zero);


SetupDiGetDeviceInterfaceDetail() always returns false, and size1
stays '0'. What am I doing wrong?
Or is there an other way in getting the device path? Maybe there is a
function returning the device path when passing the DevInst or
Reserved field from SP_DEVINFO_DATA?

Other ways I tried:
retrieving the device ID by calling CM_Get_Device_ID(); but till now I
haven't a way how to get the device path by device ID.
IoGetDeviceProperty(); but I don't know how to get PDEVICE_OBJECT
(marshalled as IntPtr) as I don't know in which .dll
IoGetDeviceObjectPointer() can be found (WineHQ tells me something
about 'ntoskrnl.dll' which cannot be found on my WinXP system; so I
tried 'ntoskrnl.exe' but got an AccessViolationException with the
explanation "Attempted to read or write protected memory. This is
often an indication that other memory is corrupt.")

As you see, I tried a lot of different ways, but couldn't find the
proper solution. Can you help me?
Thanks a lot
Christian Dankl

 

both IoXxxx calls are kernel mode APIs, not user mode APIs. what does
GetLastError (Marshal.Interop.GetLastError ?) return?

d

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