How can I find out what is wrong with a SetupDiGetClassDev interface in C#?

Question

How do I find out what's wrong with the device info set returned? I'm re-writing my code again and I'm still hitting the same stumbling block.

deviceInfoSet = SetupDiGetClassDevs(ref tGuid, 0, IntPtr.Zero, (uint)SetupDiFlags.DIGCF_PRESENT );
if (deviceInfoSet.ToInt32() == INVALID_DEVICE_HANDLE)
{
   int errCode = Marshal.GetLastWin32Error();
   errorMessage = new Win32Exception(Marshal.GetLastWin32Error()).Message;
   statusLabel.Text += "Invalid deviceinfoset returned: " + errCode + " => " + errorMessage + ".";
}

The above code doesn't cause any errors but when I use the code below:

result = true;
while (result)
{
    result = SetupDiEnumDeviceInterfaces(deviceInfoSet, IntPtr.Zero, ref tGuid, Index, ref anInterface);
    if (!result)
    {
        int errCode = Marshal.GetLastWin32Error();
        errorMessage = new Win32Exception(Marshal.GetLastWin32Error()).Message;
        statusLabel.Text += "\nSetDiEnumDeviceInterface Error: " + errCode + " => " + errorMessage + ".";
        break;
    }
    Index++;
}

to try and access the device info set list, error code 259 (No more data is available) is returned. I am at a loss as to what I'm doing wrong.

Answer 1

I'm not familiar with this particular interface but it doesn't appear you are doing anything wrong. It simply appears that you are trying to read data from a device which currently has no data to offer.

Is that the case? Do you know for sure that the device is currently trying to return data to you?

Answer 2

Are you sure you're using the right GUID?

Check out http://blogs.msdn.com/doronh/archive/2006/02/15/532679.aspx

Edit: Everything else looks by-the-book and correct.

Edit2: Trying including DIGCF_DEVICEINTERFACE in call to SetupDiGetClassDevs, and see if that works for you. That is, both DIGCF_PRESENT and DIGCF_DEVICEINTERFACE.

Edit3: For the 64bit issue (@Thies), check out http://social.msdn.microsoft.com/Forums/en-US/windowssdk/thread/ea816aea-f718-4a0e-b013-0aa273de037f

Answer 3

I had simular problems which were due to running on 64-bit Windows. I never quite figured it out, and ended up hardcoding the device path in my code - which is not recommended.

I think it has to do with the API structures not setup correct for 64-bit.

Hope this may help lead someone else to an answer (and maybe help with my problem as well)

Please state if you are running 64-bit - and have you tried the same code on a 32-bit OS?