CM_Get_DevNode_Property returns CR_INVALID_FLAG in x86 but works well on x64

See more:

C#

USB

Hello,

I hope someone can help.

I been struggling for days on this function, and it is quite hard to get an answer from the internet.

I am trying to get the location information of the child usb device, using CM_Get_DevNode_Property.

It works perfectly ok on Windows 7 x64, but fails on Windows 7 x86, with return code : CR_INVALID_FLAG

I searched and searched on the internet, but cannot find a good answer.

I do hope someone can.

Below is the code function, i used to get the location information. Thank you very much in advance.

Have a good day.

/// <summary>
/// Enumerates the node.
/// </summary>
internal void EnumerateNode()
{
    uint inst;
    int result = NativeMethods.CM_Get_Child(out inst, this.DevicePtr, 0);

    while (inst != 0)
    {
        int nBytes = 4096;
        IntPtr ptrInstanceBuf = Marshal.AllocHGlobal(nBytes);
        try
        {
            NativeMethods.CM_Get_Device_ID(inst, ptrInstanceBuf, nBytes, 0);
            string instanceID = Marshal.PtrToStringAuto(ptrInstanceBuf);

            IntPtr locationBuffer = Marshal.AllocHGlobal(nBytes);
            try
            {
                ulong size = (ulong)nBytes;
                NativeMethods.DevPropKey location = new NativeMethods.DevPropKey();
                location.guid = new Guid(0xa45c254e, 0xdf1c, 0x4efd, 0x80, 0x20, 0x67, 0xd1, 0x46, 0xa8, 0x50, 0xe0);
                location.id = NativeMethods.Device_LocationInfoId;
                ulong propType = 0;
                string locationInfo = string.Empty;
                if (NativeMethods.CM_Get_DevNode_Property(inst, location, out propType, locationBuffer, ref size, 0) == 0)
                {
                    locationInfo = Marshal.PtrToStringUni(locationBuffer);
                }

                UsbNode node = new UsbNode(instanceID, locationInfo, inst);
                this.UsbNodes.Add(node);
                node.EnumerateNode();

                NativeMethods.CM_Get_Sibling(out inst, inst, 0);
            }
            finally
            {
                Marshal.FreeHGlobal(locationBuffer);
            }
        }
        finally
        {
            Marshal.FreeHGlobal(ptrInstanceBuf);
        }
    }
}