public int sendfd ( FileDescriptor passFd ) throws IOException {
            if ( this.streamClosed ) {
                throw new AFUNIXSocketException("This OutputStream has already been closed.");
            }

            try {
                int res = NativeUnixSocket.passFd(getFD(), passFd);
                if ( res == -1 ) {
                    throw new IOException("Unspecific error while writing");
                }
                return res;
            }
            catch ( IOException e ) {
                throw (IOException) new IOException(e.getMessage() + " at " + AFUNIXSocketImpl.this.toString()).initCause(e);
            }
        }