windows/svc: add new package to help create and manage Windows services

Change-Id: I58bb446aaa387b31d8a9ff4217793a170b96a7e2
Reviewed-on: https://go-review.googlesource.com/9104
Reviewed-by: Rob Pike <r@golang.org>

windows/svc/example/install.go

@@ -0,0 +1,92 @@
+// Copyright 2012 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+// +build windows
+
+package main
+
+import (
+	"fmt"
+	"os"
+	"path/filepath"
+
+	"golang.org/x/sys/windows/svc/eventlog"
+	"golang.org/x/sys/windows/svc/mgr"
+)
+
+func exePath() (string, 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) == "" {
+		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) 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}, "is", "auto-started")
+	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
+}