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/main.go

@@ -0,0 +1,76 @@
+// 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
+
+// Example service program that beeps.
+//
+// The program demonstrates how to create Windows service and
+// install / remove it on a computer. It also shows how to
+// stop / start / pause / continue any service, and how to
+// write to event log. It also shows how to use debug
+// facilities available in debug package.
+//
+package main
+
+import (
+	"fmt"
+	"log"
+	"os"
+	"strings"
+
+	"golang.org/x/sys/windows/svc"
+)
+
+func usage(errmsg string) {
+	fmt.Fprintf(os.Stderr,
+		"%s\n\n"+
+			"usage: %s <command>\n"+
+			"       where <command> is one of\n"+
+			"       install, remove, debug, start, stop, pause or continue.\n",
+		errmsg, os.Args[0])
+	os.Exit(2)
+}
+
+func main() {
+	const svcName = "myservice"
+
+	isIntSess, err := svc.IsAnInteractiveSession()
+	if err != nil {
+		log.Fatalf("failed to determine if we are running in an interactive session: %v", err)
+	}
+	if !isIntSess {
+		runService(svcName, false)
+		return
+	}
+
+	if len(os.Args) < 2 {
+		usage("no command specified")
+	}
+
+	cmd := strings.ToLower(os.Args[1])
+	switch cmd {
+	case "debug":
+		runService(svcName, true)
+		return
+	case "install":
+		err = installService(svcName, "my service")
+	case "remove":
+		err = removeService(svcName)
+	case "start":
+		err = startService(svcName)
+	case "stop":
+		err = controlService(svcName, svc.Stop, svc.Stopped)
+	case "pause":
+		err = controlService(svcName, svc.Pause, svc.Paused)
+	case "continue":
+		err = controlService(svcName, svc.Continue, svc.Running)
+	default:
+		usage(fmt.Sprintf("invalid command %s", cmd))
+	}
+	if err != nil {
+		log.Fatalf("failed to %s %s: %v", cmd, svcName, err)
+	}
+	return
+}