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/mgr/service.go

@@ -0,0 +1,74 @@
+// 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 mgr
+
+import (
+	"syscall"
+
+	"golang.org/x/sys/windows"
+	"golang.org/x/sys/windows/svc"
+)
+
+// TODO(brainman): Use EnumDependentServices to enumerate dependent services.
+
+// TODO(brainman): Use EnumServicesStatus to enumerate services in the specified service control manager database.
+
+// Service is used to access Windows service.
+type Service struct {
+	Name   string
+	Handle windows.Handle
+}
+
+// Delete marks service s for deletion from the service control manager database.
+func (s *Service) Delete() error {
+	return windows.DeleteService(s.Handle)
+}
+
+// Close relinquish access to the service s.
+func (s *Service) Close() error {
+	return windows.CloseServiceHandle(s.Handle)
+}
+
+// Start starts service s.
+// args will be passed to svc.Handler.Execute.
+func (s *Service) Start(args ...string) error {
+	var p **uint16
+	if len(args) > 0 {
+		vs := make([]*uint16, len(args))
+		for i, _ := range vs {
+			vs[i] = syscall.StringToUTF16Ptr(args[i])
+		}
+		p = &vs[0]
+	}
+	return windows.StartService(s.Handle, uint32(len(args)), p)
+}
+
+// Control sends state change request c to the servce s.
+func (s *Service) Control(c svc.Cmd) (svc.Status, error) {
+	var t windows.SERVICE_STATUS
+	err := windows.ControlService(s.Handle, uint32(c), &t)
+	if err != nil {
+		return svc.Status{}, err
+	}
+	return svc.Status{
+		State:   svc.State(t.CurrentState),
+		Accepts: svc.Accepted(t.ControlsAccepted),
+	}, nil
+}
+
+// Query returns current status of service s.
+func (s *Service) Query() (svc.Status, error) {
+	var t windows.SERVICE_STATUS
+	err := windows.QueryServiceStatus(s.Handle, &t)
+	if err != nil {
+		return svc.Status{}, err
+	}
+	return svc.Status{
+		State:   svc.State(t.CurrentState),
+		Accepts: svc.Accepted(t.ControlsAccepted),
+	}, nil
+}