windows_svc.go

// +build !LINUX

package main

import (
	"fmt"
	"os"
	"path/filepath"
	"time"

	"github.com/wymangr/blueiris_exporter/common"
	"golang.org/x/sys/windows/svc"
	"golang.org/x/sys/windows/svc/eventlog"
	"golang.org/x/sys/windows/svc/mgr"
)

type myservice struct{}

func (m *myservice) Execute(args []string, r <-chan svc.ChangeRequest, changes chan<- svc.Status) (ssec bool, errno uint32) {

	const cmdsAccepted = svc.AcceptStop | svc.AcceptShutdown | svc.AcceptPauseAndContinue
	changes <- svc.Status{State: svc.StartPending}
	fasttick := time.Tick(500 * time.Millisecond)
	slowtick := time.Tick(2 * time.Second)
	tick := fasttick
	changes <- svc.Status{State: svc.Running, Accepts: cmdsAccepted}

	var a string = fmt.Sprintf(`starting Blue Iris Exporter with the following:
		Log Path: %v
		Metric Path: %v
		Port: %v`, os.Args[1], os.Args[2], os.Args[3])
	common.BIlogger(a, "info")

	go start(os.Args[1], os.Args[2], os.Args[3])
loop:
	for {
		select {
		case <-tick:
		case c := <-r:
			switch c.Cmd {
			case svc.Interrogate:
				changes <- c.CurrentStatus
				time.Sleep(100 * time.Millisecond)
				changes <- c.CurrentStatus
			case svc.Stop, svc.Shutdown:
				break loop
			case svc.Pause:
				changes <- svc.Status{State: svc.Paused, Accepts: cmdsAccepted}
				tick = slowtick
			case svc.Continue:
				changes <- svc.Status{State: svc.Running, Accepts: cmdsAccepted}
				tick = fasttick
			default:
				common.BIlogger(fmt.Sprintf("unexpected control request #%d", c), "error")
			}
		}
	}
	changes <- svc.Status{State: svc.StopPending}
	return
}

func IsService(name string) error {

	inService, err := svc.IsWindowsService()
	if err != nil {
		return err
	}
	if inService {
		run := svc.Run
		err = run(name, &myservice{})
		if err != nil {
			common.BIlogger(fmt.Sprintf("%s service failed: %v", name, err), "error")
			return err
		}
	}

	return nil
}

func exePath() (string, error) {
	var err error
	prog := os.Args[0]
	p, err := filepath.Abs(prog)
	if err != nil {
		return "", err
	}
	fi, err := os.Stat(p)
	if err == nil {
		if !fi.Mode().IsDir() {
			return p, nil
		}
		err = fmt.Errorf("%s is directory", p)
	}
	if filepath.Ext(p) == "" {
		var fi os.FileInfo

		p += ".exe"
		fi, err = os.Stat(p)
		if err == nil {
			if !fi.Mode().IsDir() {
				return p, nil
			}
			err = fmt.Errorf("%s is directory", p)
		}
	}
	return "", err
}

func installService(name, desc string, logpath string, metricsPath string, port string) error {
	exepath, err := exePath()
	if err != nil {
		return err
	}
	m, err := mgr.Connect()
	if err != nil {
		return err
	}
	defer m.Disconnect()
	s, err := m.OpenService(name)
	if err == nil {
		s.Close()
		return fmt.Errorf("service %s already exists", name)
	}
	s, err = m.CreateService(name, exepath, mgr.Config{DisplayName: desc}, logpath, metricsPath, port)
	if err != nil {
		return err
	}
	defer s.Close()
	err = eventlog.InstallAsEventCreate(name, eventlog.Error|eventlog.Warning|eventlog.Info)
	if err != nil {
		s.Delete()
		return fmt.Errorf("SetupEventLogSource() failed: %s", err)
	}
	return nil
}

func removeService(name string) error {
	m, err := mgr.Connect()
	if err != nil {
		return err
	}
	defer m.Disconnect()
	s, err := m.OpenService(name)
	if err != nil {
		return fmt.Errorf("service %s is not installed", name)
	}
	defer s.Close()
	err = s.Delete()
	if err != nil {
		return err
	}
	err = eventlog.Remove(name)
	if err != nil {
		return fmt.Errorf("RemoveEventLogSource() failed: %s", err)
	}
	return nil
}

func startService(name string) error {
	m, err := mgr.Connect()
	if err != nil {
		return err
	}
	defer m.Disconnect()
	s, err := m.OpenService(name)
	if err != nil {
		return fmt.Errorf("could not access service: %v", err)
	}
	defer s.Close()

	err = s.Start()
	if err != nil {
		return fmt.Errorf("could not start service: %v", err)
	}
	return nil
}

func controlService(name string, command string) error {

	var c svc.Cmd
	var to svc.State

	switch command {
	case "Stop":
		c = svc.Stop
		to = svc.Stopped
	case "Pause":
		c = svc.Pause
		to = svc.Paused
	case "Continue":
		c = svc.Continue
		to = svc.Running

	}
	m, err := mgr.Connect()
	if err != nil {
		return err
	}
	defer m.Disconnect()
	s, err := m.OpenService(name)
	if err != nil {
		return fmt.Errorf("could not access service: %v", err)
	}
	defer s.Close()
	status, err := s.Control(c)
	if err != nil {
		return fmt.Errorf("could not send control=%d: %v", c, err)
	}
	timeout := time.Now().Add(10 * time.Second)
	for status.State != to {
		if timeout.Before(time.Now()) {
			return fmt.Errorf("timeout waiting for service to go to state=%d", to)
		}
		time.Sleep(300 * time.Millisecond)
		status, err = s.Query()
		if err != nil {
			return fmt.Errorf("could not retrieve service status: %v", err)
		}
	}
	return nil
}