// In "SBooting", we have a pid and socket to the process we will use,
// but it has not yet finished initializing (generally, running the code
// specific to this slave). When we receive a message about the success or
// failure of this operation, we transition to either crashed or ready.
func (s *SlaveNode) doBootingState() string { // -> {SCrashed, SReady}
	// The slave will execute its action and respond with a status...
	// Note we don't hold the mutex while waiting for the action to execute.
	msg, err := s.socket.ReadMessage()
	if err != nil {
		s.L.Lock()
		defer s.L.Unlock()
		s.Error = err.Error()
		slog.ErrorString("[" + s.Name + "] " + err.Error())

		return SCrashed
	}

	s.trace("received action message")
	s.L.Lock()
	defer s.L.Unlock()

	msg, err = messages.ParseActionResponseMessage(msg)
	if err != nil {
		slog.ErrorString("[" + s.Name + "] " + err.Error())
	}
	if msg == "OK" {
		return SReady
	}

	// Clean up:
	if s.pid > 0 {
		syscall.Kill(s.pid, syscall.SIGKILL)
	}
	s.wipe()
	s.Error = msg
	return SCrashed
}

// In "SBooting", we have a pid and socket to the process we will use,
// but it has not yet finished initializing (generally, running the code
// specific to this slave. When we receive a message about the success or
// failure of this operation, we transition to either crashed or ready.
func (s *SlaveNode) doBootingState() string { // -> {SCrashed, SReady}
	// The slave will execute its action and respond with a status...
	// Note we don't hold the mutex while waiting for the action to execute.
	msg, err := s.socket.ReadMessage()
	if err != nil {
		slog.Error(err)
	}
	s.trace("in booting state")
	s.L.Lock()
	defer s.L.Unlock()

	msg, err = messages.ParseActionResponseMessage(msg)
	if err != nil {
		slog.ErrorString("[" + s.Name + "] " + err.Error())
	}
	if msg == "OK" {
		return SReady
	}

	// Drain the process's feature messages, if we have any, so
	// that reloads happen when any load-time problems get fixed:
	s.L.Unlock()
	s.handleMessages()
	s.L.Lock()

	// Clean up:
	if s.Pid > 0 {
		syscall.Kill(s.Pid, syscall.SIGKILL)
	}
	s.wipe()
	s.Error = msg
	return SCrashed
}

func sendCommandLineArguments(usock *unixsocket.Usock, args []string) error {
	master, slave, err := unixsocket.Socketpair(syscall.SOCK_STREAM)
	if err != nil {
		return err
	}
	usock.WriteFD(int(slave.Fd()))
	if err != nil {
		return err
	}
	slave.Close()

	go func() {
		defer master.Close()
		argAsBytes := []byte{}
		for _, arg := range args[1:] {
			argAsBytes = append(argAsBytes, []byte(arg)...)
			argAsBytes = append(argAsBytes, byte(0))
		}
		_, err = master.Write(argAsBytes)
		if err != nil {
			slog.ErrorString("Could not send arguments across: " +
				err.Error() + "\r")
			return
		}
	}()

	return nil
}

func (s *SlaveNode) SlaveWasInitialized(pid int, usock *unixsocket.Usock) {
	s.L.Lock()
	s.wipe()
	s.Pid = pid
	s.socket = usock
	if s.state == sUnbooted {
		s.event <- true
	} else {
		if pid > 0 {
			syscall.Kill(pid, syscall.SIGKILL)
		}
		slog.ErrorString("Unexpected process for slave `" + s.Name + "` was killed")
	}
	s.L.Unlock()
}

func (s *SlaveNode) SlaveWasInitialized(pid int, usock *unixsocket.Usock, featurePipeFd int) {
	file := os.NewFile(uintptr(featurePipeFd), "featurepipe")

	s.L.Lock()
	s.wipe()
	s.featurePipe = file
	s.Pid = pid
	s.socket = usock
	if s.State == SUnbooted {
		s.event <- true
	} else {
		if pid > 0 {
			syscall.Kill(pid, syscall.SIGKILL)
		}
		slog.ErrorString("Unexpected process for slave `" + s.Name + "` was killed")
	}
	s.L.Unlock()
}

func (s *SlaveNode) SlaveWasInitialized(pid, parentPid int, usock *unixsocket.Usock, featurePipeFd int) {
	file := os.NewFile(uintptr(featurePipeFd), "featurepipe")

	s.L.Lock()
	if !s.ReportBootEvent() {
		if pid > 0 {
			syscall.Kill(pid, syscall.SIGKILL)
		}
		slog.ErrorString(fmt.Sprintf("Unexpected process %d with parent %d for slave %q was killed", pid, parentPid, s.Name))
	} else {
		s.wipe()
		s.pid = pid
		s.socket = usock
		go s.handleMessages(file)
		s.trace("initialized slave %s with pid %d from parent %d", s.Name, pid, parentPid)
	}
	s.L.Unlock()
}

func Run(args []string, input io.Reader, output *os.File) int {
	if os.Getenv("RAILS_ENV") != "" {
		println("Warning: Specifying a Rails environment via RAILS_ENV has no effect for commands run with zeus.")
		println("As a safety precaution to protect you from nuking your development database,")
		println("Zeus will now cowardly refuse to proceed. Please unset RAILS_ENV and try again.")
		return 1
	}

	isTerminal := ttyutils.IsTerminal(output.Fd())

	var master, slave *os.File
	var err error
	if isTerminal {
		master, slave, err = pty.Open()
	} else {
		master, slave, err = unixsocket.Socketpair(syscall.SOCK_STREAM)
	}
	if err != nil {
		slog.ErrorString(err.Error() + "\r")
		return 1
	}

	defer master.Close()
	var oldState *ttyutils.Termios
	if isTerminal {
		oldState, err = ttyutils.MakeTerminalRaw(output.Fd())
		if err != nil {
			slog.ErrorString(err.Error() + "\r")
			return 1
		}
		defer ttyutils.RestoreTerminalState(output.Fd(), oldState)
	}

	// should this happen if we're running over a pipe? I think maybe not?
	ttyutils.MirrorWinsize(output, master)

	addr, err := net.ResolveUnixAddr("unixgram", unixsocket.ZeusSockName())
	if err != nil {
		slog.ErrorString(err.Error() + "\r")
		return 1
	}

	conn, err := net.DialUnix("unix", nil, addr)
	if err != nil {
		zerror.ErrorCantConnectToMaster()
		return 1
	}
	usock := unixsocket.New(conn)

	msg := messages.CreateCommandAndArgumentsMessage(args, os.Getpid())
	usock.WriteMessage(msg)
	err = sendCommandLineArguments(usock, args)
	if err != nil {
		slog.ErrorString(err.Error() + "\r")
		return 1
	}

	usock.WriteFD(int(slave.Fd()))
	slave.Close()

	msg, err = usock.ReadMessage()
	if err != nil {
		slog.ErrorString(err.Error() + "\r")
		return 1
	}

	parts := strings.Split(msg, "\000")
	commandPid, err := strconv.Atoi(parts[0])
	defer func() {
		if commandPid > 0 {
			// Just in case.
			syscall.Kill(commandPid, 9)
		}
	}()

	if err != nil {
		slog.ErrorString(err.Error() + "\r")
		return 1
	}

	if isTerminal {
		c := make(chan os.Signal, 1)
		handledSignals := append(append(terminatingSignals, syscall.SIGWINCH), syscall.SIGCONT)
		signal.Notify(c, handledSignals...)
		go func() {
			for sig := range c {
				if sig == syscall.SIGCONT {
					syscall.Kill(commandPid, syscall.SIGCONT)
				} else if sig == syscall.SIGWINCH {
					ttyutils.MirrorWinsize(output, master)
					syscall.Kill(commandPid, syscall.SIGWINCH)
				} else { // member of terminatingSignals
					ttyutils.RestoreTerminalState(output.Fd(), oldState)
					print("\r")
					syscall.Kill(commandPid, sig.(syscall.Signal))
					os.Exit(1)
				}
			}
		}()
	}
//.........这里部分代码省略.........