// Copyright (c) 2026 Petr Balvín <opensource@petrbalvin.org> (https://petrbalvin.org)
// SPDX-License-Identifier: MIT

package main

import (
	"errors"
	"log"
	"net"
	"os"
)

// notifyReady announces readiness to the service manager over
// $NOTIFY_SOCKET, the raw unix datagram socket of the sd_notify
// protocol. The message is the one READY=1 line; nothing else is sent
// and no dependency is pulled in. Without the variable, the process is
// not running under a Type=notify unit and the step is skipped quietly.
func notifyReady() error {
	addr := os.Getenv("NOTIFY_SOCKET")
	if addr == "" {
		return nil
	}
	conn, err := net.DialUnix("unixgram", nil, &net.UnixAddr{Name: addr, Net: "unixgram"})
	if err != nil {
		return err
	}
	defer conn.Close()
	if _, err := conn.Write([]byte("READY=1")); err != nil {
		return err
	}
	return nil
}

// notifyReadyOrLog announces readiness and reports a failure on the log
// without ending the service: a manager that expects the notification
// times the unit out, but the server itself is ready to serve either way.
func notifyReadyOrLog() {
	if err := notifyReady(); err != nil && !errors.Is(err, os.ErrNotExist) {
		log.Printf("nfsd: the readiness notification failed: %v", err)
	}
}