daemon.go

// Copyright 2019 Northern.tech AS
//
//    Licensed under the Apache License, Version 2.0 (the "License");
//    you may not use this file except in compliance with the License.
//    You may obtain a copy of the License at
//
//        http://www.apache.org/licenses/LICENSE-2.0
//
//    Unless required by applicable law or agreed to in writing, software
//    distributed under the License is distributed on an "AS IS" BASIS,
//    WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
//    See the License for the specific language governing permissions and
//    limitations under the License.
package main

import (
	"os"

	"github.com/mendersoftware/log"
	"github.com/mendersoftware/mender/datastore"
	"github.com/mendersoftware/mender/store"
	"github.com/mendersoftware/mender/system"
	"github.com/pkg/errors"
)

// Config section

type menderDaemon struct {
	mender      Controller
	stop        bool
	sctx        StateContext
	store       store.Store
	updateCheck chan bool // state-machine interrupt.
}

func NewDaemon(mender Controller, store store.Store) *menderDaemon {

	daemon := menderDaemon{
		mender: mender,
		sctx: StateContext{
			store:    store,
			rebooter: system.NewSystemRebootCmd(system.OsCalls{}),
		},
		store:       store,
		updateCheck: make(chan bool, 1),
	}
	return &daemon
}

func (d *menderDaemon) StopDaemon() {
	d.stop = true
}

func (d *menderDaemon) Cleanup() {
	if d.store != nil {
		if err := d.store.Close(); err != nil {
			log.Errorf("failed to close data store: %v", err)
		}
		d.store = nil
	}
}

func (d *menderDaemon) shouldStop() bool {
	return d.stop
}

func (d *menderDaemon) Run() error {
	// set the first state transition
	var toState State = d.mender.GetCurrentState()
	cancelled := false
	for {
		// If signal SIGUSR1 received, check for update straight away.
		select {
		case sig := <-d.updateCheck:
			log.Debugf("received signal: %t", sig)
			_, err := LoadStateData(d.sctx.store)
			// No previous state stored, means no update was in progress,
			// and we can safely force an update check.
			if err != nil && os.IsNotExist(err) {
				if d.mender.IsAuthorized() {
					toState = updateCheckState
				} else {
					toState = initState
				}
				d.mender.SetNextState(toState)
			}
		default:
			// Identity op - do nothing.
		}
		toState, cancelled = d.mender.TransitionState(toState, &d.sctx)
		if toState.Id() == datastore.MenderStateError {
			es, ok := toState.(*ErrorState)
			if ok {
				if es.IsFatal() {
					return es.cause
				}
			} else {
				return errors.New("failed")
			}
		}
		if cancelled || toState.Id() == datastore.MenderStateDone {
			break
		}
		if d.shouldStop() {
			return nil
		}
	}
	return nil
}