sd_notify in Java using junixsocket

SdNotify.java

/*
Permission to use, copy, modify, and/or distribute this software for
any purpose with or without fee is hereby granted.

THE SOFTWARE IS PROVIDED “AS IS” AND THE AUTHOR DISCLAIMS ALL
WARRANTIES WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES
OF MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE
FOR ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY
DAMAGES WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN
AN ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT
OF OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
*/

// Test using the following command:
// systemd-run --user --pty --same-dir --wait --collect --service-type=notify -p NotifyAccess=all java -cp junixsocket.jar SdNotify.jav
// Should state: "Finished with result: success"
// In case of failure due to wrong sd_notify usage, it will state: "Finished with result: protocol"

import java.io.IOException;
import java.nio.ByteBuffer;

import org.newsclub.net.unix.AFUNIXDatagramSocket;
import org.newsclub.net.unix.AFUNIXSocketAddress;

public class SdNotify {
    public static void main(String[] args) {
        ready();
    }

    public static void ready() {
        notify("READY=1");
    }

    public static void status(String status) {
        notify("STATUS=" + status);
    }

    /// ...implement other well-known sd_notify(3) messages as needed...

    private static void notify(String arg) {
        var socketPath = System.getenv("NOTIFY_SOCKET");
        if (socketPath == null)
            return;

        if (!(socketPath.startsWith("/") || socketPath.startsWith("@"))) {
            throw new UnsupportedOperationException("Unsupported socket type");
        }

        if (socketPath.startsWith("@")) {
            socketPath = "\0" + socketPath.substring(1);
        }

        try (var socket = AFUNIXDatagramSocket.newInstance()) {
            socket.connect(AFUNIXSocketAddress.of(socketPath.getBytes()));

            try (var out = socket.getChannel()) {
                out.write(ByteBuffer.wrap(arg.getBytes()));
            }
        } catch (IOException e) {
            System.err.printf("Failed to notify systemd of service readiness: %s", e.toString());
        }
    }
}