wchar_t* NTAPI TestUnicode()
{
    return L"<\xD1\xD1\xD1\xD0\xAE\xA9>\0\0";  //CCCP
}

        [DllImport("unittest.dll", CharSet = CharSet.Unicode, ExactSpelling = true, CallingConvention = CallingConvention.StdCall)]
        public static extern IntPtr TestUnicode();        //


        protected bool foo()
        {
            IntPtr ptrUserList = TestUnicode();
            string userList = Marshal.PtrToStringUni(ptrUserList);
    }