Checking in vendor folder for ease of using go get.

vendor/golang.org/x/sys/windows/svc/service.go

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+// 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 svc provides everything required to build Windows service.
+//
+package svc
+
+import (
+	"errors"
+	"runtime"
+	"syscall"
+	"unsafe"
+
+	"golang.org/x/sys/windows"
+)
+
+// State describes service execution state (Stopped, Running and so on).
+type State uint32
+
+const (
+	Stopped         = State(windows.SERVICE_STOPPED)
+	StartPending    = State(windows.SERVICE_START_PENDING)
+	StopPending     = State(windows.SERVICE_STOP_PENDING)
+	Running         = State(windows.SERVICE_RUNNING)
+	ContinuePending = State(windows.SERVICE_CONTINUE_PENDING)
+	PausePending    = State(windows.SERVICE_PAUSE_PENDING)
+	Paused          = State(windows.SERVICE_PAUSED)
+)
+
+// Cmd represents service state change request. It is sent to a service
+// by the service manager, and should be actioned upon by the service.
+type Cmd uint32
+
+const (
+	Stop                  = Cmd(windows.SERVICE_CONTROL_STOP)
+	Pause                 = Cmd(windows.SERVICE_CONTROL_PAUSE)
+	Continue              = Cmd(windows.SERVICE_CONTROL_CONTINUE)
+	Interrogate           = Cmd(windows.SERVICE_CONTROL_INTERROGATE)
+	Shutdown              = Cmd(windows.SERVICE_CONTROL_SHUTDOWN)
+	ParamChange           = Cmd(windows.SERVICE_CONTROL_PARAMCHANGE)
+	NetBindAdd            = Cmd(windows.SERVICE_CONTROL_NETBINDADD)
+	NetBindRemove         = Cmd(windows.SERVICE_CONTROL_NETBINDREMOVE)
+	NetBindEnable         = Cmd(windows.SERVICE_CONTROL_NETBINDENABLE)
+	NetBindDisable        = Cmd(windows.SERVICE_CONTROL_NETBINDDISABLE)
+	DeviceEvent           = Cmd(windows.SERVICE_CONTROL_DEVICEEVENT)
+	HardwareProfileChange = Cmd(windows.SERVICE_CONTROL_HARDWAREPROFILECHANGE)
+	PowerEvent            = Cmd(windows.SERVICE_CONTROL_POWEREVENT)
+	SessionChange         = Cmd(windows.SERVICE_CONTROL_SESSIONCHANGE)
+)
+
+// Accepted is used to describe commands accepted by the service.
+// Note that Interrogate is always accepted.
+type Accepted uint32
+
+const (
+	AcceptStop                  = Accepted(windows.SERVICE_ACCEPT_STOP)
+	AcceptShutdown              = Accepted(windows.SERVICE_ACCEPT_SHUTDOWN)
+	AcceptPauseAndContinue      = Accepted(windows.SERVICE_ACCEPT_PAUSE_CONTINUE)
+	AcceptParamChange           = Accepted(windows.SERVICE_ACCEPT_PARAMCHANGE)
+	AcceptNetBindChange         = Accepted(windows.SERVICE_ACCEPT_NETBINDCHANGE)
+	AcceptHardwareProfileChange = Accepted(windows.SERVICE_ACCEPT_HARDWAREPROFILECHANGE)
+	AcceptPowerEvent            = Accepted(windows.SERVICE_ACCEPT_POWEREVENT)
+	AcceptSessionChange         = Accepted(windows.SERVICE_ACCEPT_SESSIONCHANGE)
+)
+
+// Status combines State and Accepted commands to fully describe running service.
+type Status struct {
+	State      State
+	Accepts    Accepted
+	CheckPoint uint32 // used to report progress during a lengthy operation
+	WaitHint   uint32 // estimated time required for a pending operation, in milliseconds
+}
+
+// ChangeRequest is sent to the service Handler to request service status change.
+type ChangeRequest struct {
+	Cmd           Cmd
+	EventType     uint32
+	EventData     uintptr
+	CurrentStatus Status
+}
+
+// Handler is the interface that must be implemented to build Windows service.
+type Handler interface {
+
+	// Execute will be called by the package code at the start of
+	// the service, and the service will exit once Execute completes.
+	// Inside Execute you must read service change requests from r and
+	// act accordingly. You must keep service control manager up to date
+	// about state of your service by writing into s as required.
+	// args contains service name followed by argument strings passed
+	// to the service.
+	// You can provide service exit code in exitCode return parameter,
+	// with 0 being "no error". You can also indicate if exit code,
+	// if any, is service specific or not by using svcSpecificEC
+	// parameter.
+	Execute(args []string, r <-chan ChangeRequest, s chan<- Status) (svcSpecificEC bool, exitCode uint32)
+}
+
+var (
+	// These are used by asm code.
+	goWaitsH                       uintptr
+	cWaitsH                        uintptr
+	ssHandle                       uintptr
+	sName                          *uint16
+	sArgc                          uintptr
+	sArgv                          **uint16
+	ctlHandlerExProc               uintptr
+	cSetEvent                      uintptr
+	cWaitForSingleObject           uintptr
+	cRegisterServiceCtrlHandlerExW uintptr
+)
+
+func init() {
+	k := syscall.MustLoadDLL("kernel32.dll")
+	cSetEvent = k.MustFindProc("SetEvent").Addr()
+	cWaitForSingleObject = k.MustFindProc("WaitForSingleObject").Addr()
+	a := syscall.MustLoadDLL("advapi32.dll")
+	cRegisterServiceCtrlHandlerExW = a.MustFindProc("RegisterServiceCtrlHandlerExW").Addr()
+}
+
+// The HandlerEx prototype also has a context pointer but since we don't use
+// it at start-up time we don't have to pass it over either.
+type ctlEvent struct {
+	cmd       Cmd
+	eventType uint32
+	eventData uintptr
+	errno     uint32
+}
+
+// service provides access to windows service api.
+type service struct {
+	name    string
+	h       windows.Handle
+	cWaits  *event
+	goWaits *event
+	c       chan ctlEvent
+	handler Handler
+}
+
+func newService(name string, handler Handler) (*service, error) {
+	var s service
+	var err error
+	s.name = name
+	s.c = make(chan ctlEvent)
+	s.handler = handler
+	s.cWaits, err = newEvent()
+	if err != nil {
+		return nil, err
+	}
+	s.goWaits, err = newEvent()
+	if err != nil {
+		s.cWaits.Close()
+		return nil, err
+	}
+	return &s, nil
+}
+
+func (s *service) close() error {
+	s.cWaits.Close()
+	s.goWaits.Close()
+	return nil
+}
+
+type exitCode struct {
+	isSvcSpecific bool
+	errno         uint32
+}
+
+func (s *service) updateStatus(status *Status, ec *exitCode) error {
+	if s.h == 0 {
+		return errors.New("updateStatus with no service status handle")
+	}
+	var t windows.SERVICE_STATUS
+	t.ServiceType = windows.SERVICE_WIN32_OWN_PROCESS
+	t.CurrentState = uint32(status.State)
+	if status.Accepts&AcceptStop != 0 {
+		t.ControlsAccepted |= windows.SERVICE_ACCEPT_STOP
+	}
+	if status.Accepts&AcceptShutdown != 0 {
+		t.ControlsAccepted |= windows.SERVICE_ACCEPT_SHUTDOWN
+	}
+	if status.Accepts&AcceptPauseAndContinue != 0 {
+		t.ControlsAccepted |= windows.SERVICE_ACCEPT_PAUSE_CONTINUE
+	}
+	if status.Accepts&AcceptParamChange != 0 {
+		t.ControlsAccepted |= windows.SERVICE_ACCEPT_PARAMCHANGE
+	}
+	if status.Accepts&AcceptNetBindChange != 0 {
+		t.ControlsAccepted |= windows.SERVICE_ACCEPT_NETBINDCHANGE
+	}
+	if status.Accepts&AcceptHardwareProfileChange != 0 {
+		t.ControlsAccepted |= windows.SERVICE_ACCEPT_HARDWAREPROFILECHANGE
+	}
+	if status.Accepts&AcceptPowerEvent != 0 {
+		t.ControlsAccepted |= windows.SERVICE_ACCEPT_POWEREVENT
+	}
+	if status.Accepts&AcceptSessionChange != 0 {
+		t.ControlsAccepted |= windows.SERVICE_ACCEPT_SESSIONCHANGE
+	}
+	if ec.errno == 0 {
+		t.Win32ExitCode = windows.NO_ERROR
+		t.ServiceSpecificExitCode = windows.NO_ERROR
+	} else if ec.isSvcSpecific {
+		t.Win32ExitCode = uint32(windows.ERROR_SERVICE_SPECIFIC_ERROR)
+		t.ServiceSpecificExitCode = ec.errno
+	} else {
+		t.Win32ExitCode = ec.errno
+		t.ServiceSpecificExitCode = windows.NO_ERROR
+	}
+	t.CheckPoint = status.CheckPoint
+	t.WaitHint = status.WaitHint
+	return windows.SetServiceStatus(s.h, &t)
+}
+
+const (
+	sysErrSetServiceStatusFailed = uint32(syscall.APPLICATION_ERROR) + iota
+	sysErrNewThreadInCallback
+)
+
+func (s *service) run() {
+	s.goWaits.Wait()
+	s.h = windows.Handle(ssHandle)
+	argv := (*[100]*int16)(unsafe.Pointer(sArgv))[:sArgc]
+	args := make([]string, len(argv))
+	for i, a := range argv {
+		args[i] = syscall.UTF16ToString((*[1 << 20]uint16)(unsafe.Pointer(a))[:])
+	}
+
+	cmdsToHandler := make(chan ChangeRequest)
+	changesFromHandler := make(chan Status)
+	exitFromHandler := make(chan exitCode)
+
+	go func() {
+		ss, errno := s.handler.Execute(args, cmdsToHandler, changesFromHandler)
+		exitFromHandler <- exitCode{ss, errno}
+	}()
+
+	status := Status{State: Stopped}
+	ec := exitCode{isSvcSpecific: true, errno: 0}
+	var outch chan ChangeRequest
+	inch := s.c
+	var cmd Cmd
+	var evtype uint32
+	var evdata uintptr
+loop:
+	for {
+		select {
+		case r := <-inch:
+			if r.errno != 0 {
+				ec.errno = r.errno
+				break loop
+			}
+			inch = nil
+			outch = cmdsToHandler
+			cmd = r.cmd
+			evtype = r.eventType
+			evdata = r.eventData
+		case outch <- ChangeRequest{cmd, evtype, evdata, status}:
+			inch = s.c
+			outch = nil
+		case c := <-changesFromHandler:
+			err := s.updateStatus(&c, &ec)
+			if err != nil {
+				// best suitable error number
+				ec.errno = sysErrSetServiceStatusFailed
+				if err2, ok := err.(syscall.Errno); ok {
+					ec.errno = uint32(err2)
+				}
+				break loop
+			}
+			status = c
+		case ec = <-exitFromHandler:
+			break loop
+		}
+	}
+
+	s.updateStatus(&Status{State: Stopped}, &ec)
+	s.cWaits.Set()
+}
+
+func newCallback(fn interface{}) (cb uintptr, err error) {
+	defer func() {
+		r := recover()
+		if r == nil {
+			return
+		}
+		cb = 0
+		switch v := r.(type) {
+		case string:
+			err = errors.New(v)
+		case error:
+			err = v
+		default:
+			err = errors.New("unexpected panic in syscall.NewCallback")
+		}
+	}()
+	return syscall.NewCallback(fn), nil
+}
+
+// BUG(brainman): There is no mechanism to run multiple services
+// inside one single executable. Perhaps, it can be overcome by
+// using RegisterServiceCtrlHandlerEx Windows api.
+
+// Run executes service name by calling appropriate handler function.
+func Run(name string, handler Handler) error {
+	runtime.LockOSThread()
+
+	tid := windows.GetCurrentThreadId()
+
+	s, err := newService(name, handler)
+	if err != nil {
+		return err
+	}
+
+	ctlHandler := func(ctl uint32, evtype uint32, evdata uintptr, context uintptr) uintptr {
+		e := ctlEvent{cmd: Cmd(ctl), eventType: evtype, eventData: evdata}
+		// We assume that this callback function is running on
+		// the same thread as Run. Nowhere in MS documentation
+		// I could find statement to guarantee that. So putting
+		// check here to verify, otherwise things will go bad
+		// quickly, if ignored.
+		i := windows.GetCurrentThreadId()
+		if i != tid {
+			e.errno = sysErrNewThreadInCallback
+		}
+		s.c <- e
+		// Always return NO_ERROR (0) for now.
+		return 0
+	}
+
+	var svcmain uintptr
+	getServiceMain(&svcmain)
+	t := []windows.SERVICE_TABLE_ENTRY{
+		{ServiceName: syscall.StringToUTF16Ptr(s.name), ServiceProc: svcmain},
+		{ServiceName: nil, ServiceProc: 0},
+	}
+
+	goWaitsH = uintptr(s.goWaits.h)
+	cWaitsH = uintptr(s.cWaits.h)
+	sName = t[0].ServiceName
+	ctlHandlerExProc, err = newCallback(ctlHandler)
+	if err != nil {
+		return err
+	}
+
+	go s.run()
+
+	err = windows.StartServiceCtrlDispatcher(&t[0])
+	if err != nil {
+		return err
+	}
+	return nil
+}
+
+// StatusHandle returns service status handle. It is safe to call this function
+// from inside the Handler.Execute because then it is guaranteed to be set.
+// This code will have to change once multiple services are possible per process.
+func StatusHandle() windows.Handle {
+	return windows.Handle(ssHandle)
+}