Why is ICreateDeviceAccessAsync::GetResult returning E_INVALIDARG?

Question

I am trying to access a custom driver using IO control codes from a Metro app.  I have already done this successfully using a desktop app.  I am doing the following for the Metro app:

ICreateDeviceAccessAsync *access;
HRESULT hr = CreateDeviceAccessInstance(IID_IDeviceIoControl, L"\\\\.\\MyDevice", GENERIC_READ | GENERIC_WRITE, &access);
if (SUCCEEDED(hr))
{
    hr = access->Start();
    if (SUCCEEDED(hr))
    {
        hr = access->Wait(INFINITE);
        if (SUCCEEDED(hr))
        {
            IDeviceIoControl *control;
            hr = access->GetResult(reinterpret_cast<void **>(&control));
            if (SUCCEEDED(hr))
            {
            }
        }
    }
    access->Release();
}

The GetResult call is returning E_INVALIDARG.  I have not configured the device metadata for my driver, so I would expect this call to return E_ACCESSDENIED instead.  Why would this call return E_INVALIDARG?

Answer 1

Thunk Monkey,

I will look into this for you.  Does the code work once you define the metadata?

 

Best Wishes - Eric

Answer 2

I have not yet defined metadata for my driver, but in that case I would expect E_ACCESSDENIED instead of E_INVALIDARG.

One thing I noticed is that if I use a device path that begins with \\?\ instead of \\.\, I get a "not found" error or an "access denied" error instead of an "invalid argument" error.  This suggests to me that CreateDeviceAccessInstance cannot accept a symbolic or MS-DOS device name the same way that CreateFile can.  Is this true?

Answer 3

You're correct; the API only works for device interface paths (e.g. \\?\USB#VID_0B0E&PID_2007#5&28ab2847&0&1#{a5dcbf10-6530-11d2-901f-00c04fb951ed}).

Answer 4

Hi all,

I still get invalid arg HRESULT from GetResult..

I'm using VS2011 with customer preview version.

Is there any solution?

I cannot find any resource for reference..

Thanks.

Answer 5

James,

Could you try with this sample?

http://code.msdn.microsoft.com/windowsapps/Custom-device-access-sample-43bde679

Best Wishes - Eric