vendor/github.com/coreos/go-systemd/examples/activation/udpconn.go

// Copyright 2015 CoreOS, Inc.
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
//     http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.

// +build ignore

// Activation example used by the activation unit tests.
package main

import (
	"fmt"
	"net"
	"os"

	"github.com/coreos/go-systemd/activation"
)

func fixListenPid() {
	if os.Getenv("FIX_LISTEN_PID") != "" {
		// HACK: real systemd would set LISTEN_PID before exec'ing but
		// this is too difficult in golang for the purpose of a test.
		// Do not do this in real code.
		os.Setenv("LISTEN_PID", fmt.Sprintf("%d", os.Getpid()))
	}
}

func main() {
	fixListenPid()

	pc, err := activation.PacketConns()
	if err != nil {
		panic(err)
	}

	if os.Getenv("LISTEN_PID") != "" || os.Getenv("LISTEN_FDS") != "" || os.Getenv("LISTEN_FDNAMES") != "" {
		panic("Can not unset envs")
	}

	udp1, ok := pc[0].(*net.UDPConn)
	if !ok {
		panic("packetConn 1 not UDP")
	}
	udp2, ok := pc[1].(*net.UDPConn)
	if !ok {
		panic("packetConn 2 not UDP")
	}

	_, addr1, err := udp1.ReadFromUDP(nil)
	if err != nil {
		panic(err)
	}
	_, addr2, err := udp2.ReadFromUDP(nil)
	if err != nil {
		panic(err)
	}

	// Write out the expected strings to the two pipes
	_, err = udp1.WriteToUDP([]byte("Hello world"), addr1)
	if err != nil {
		panic(err)
	}
	_, err = udp2.WriteToUDP([]byte("Goodbye world"), addr2)
	if err != nil {
		panic(err)
	}

	return
}