System.IO.FileStream.VerifyHandleIsSync C# (CSharp) Method

        private unsafe void VerifyHandleIsSync()
        {
            Debug.Assert(!_useAsyncIO);

            // Do NOT use this method on pipes.  Reading or writing to a pipe may
            // cause an app to block incorrectly, introducing a deadlock (depending
            // on whether a write will wake up an already-blocked thread or this
            // Win32FileStream's thread).
            Debug.Assert(Interop.Kernel32.GetFileType(_fileHandle) != Interop.Kernel32.FileTypes.FILE_TYPE_PIPE);

            byte* bytes = stackalloc byte[1];
            int numBytesReadWritten;
            int r = -1;

            // If the handle is a pipe, ReadFile will block until there
            // has been a write on the other end.  We'll just have to deal with it,
            // For the read end of a pipe, you can mess up and 
            // accidentally read synchronously from an async pipe.
            if ((_access & FileAccess.Read) != 0) // don't use the virtual CanRead or CanWrite, as this may be used in the ctor
            {
                r = Interop.Kernel32.ReadFile(_fileHandle, bytes, 0, out numBytesReadWritten, IntPtr.Zero);
            }
            else if ((_access & FileAccess.Write) != 0) // don't use the virtual CanRead or CanWrite, as this may be used in the ctor
            {
                r = Interop.Kernel32.WriteFile(_fileHandle, bytes, 0, out numBytesReadWritten, IntPtr.Zero);
            }

            if (r == 0)
            {
                int errorCode = GetLastWin32ErrorAndDisposeHandleIfInvalid(throwIfInvalidHandle: true);
                if (errorCode == ERROR_INVALID_PARAMETER)
                    throw new ArgumentException(SR.Arg_HandleNotSync, "handle");
            }
        }