package daemon
 
 import (
 	"fmt"
 

 	"github.com/docker/docker/api/types/container"

 	"github.com/pkg/errors"

 )
 

 // ContainerUpdate updates configuration of the container

 func (daemon *Daemon) ContainerUpdate(name string, hostConfig *container.HostConfig) (container.ContainerUpdateOKBody, error) {

 	var warnings []string
 

 	c, err := daemon.GetContainer(name)
 	if err != nil {
 		return container.ContainerUpdateOKBody{Warnings: warnings}, err
 	}
 

 	warnings, err = daemon.verifyContainerSettings(c.OS, hostConfig, nil, true)

 	if err != nil {

 		return container.ContainerUpdateOKBody{Warnings: warnings}, validationError{err}

 	}
 
 	if err := daemon.update(name, hostConfig); err != nil {

 		return container.ContainerUpdateOKBody{Warnings: warnings}, err

 	}
 

 	return container.ContainerUpdateOKBody{Warnings: warnings}, nil

 }
 
 func (daemon *Daemon) update(name string, hostConfig *container.HostConfig) error {
 	if hostConfig == nil {
 		return nil
 	}
 
 	container, err := daemon.GetContainer(name)
 	if err != nil {
 		return err
 	}
 

 	restoreConfig := false
 	backupHostConfig := *container.HostConfig
 	defer func() {
 		if restoreConfig {
 			container.Lock()
 			container.HostConfig = &backupHostConfig

 			container.CheckpointTo(daemon.containersReplica)

 			container.Unlock()
 		}
 	}()
 

 	if container.RemovalInProgress || container.Dead {

 		return errCannotUpdate(container.ID, fmt.Errorf("container is marked for removal and cannot be \"update\""))

 	}
 

 	container.Lock()

 	if err := container.UpdateContainer(hostConfig); err != nil {

 		restoreConfig = true

 		container.Unlock()

 		return errCannotUpdate(container.ID, err)

 	}

 	if err := container.CheckpointTo(daemon.containersReplica); err != nil {

 		restoreConfig = true
 		container.Unlock()
 		return errCannotUpdate(container.ID, err)
 	}
 	container.Unlock()

 	// if Restart Policy changed, we need to update container monitor

 	if hostConfig.RestartPolicy.Name != "" {
 		container.UpdateMonitor(hostConfig.RestartPolicy)
 	}

 	// If container is not running, update hostConfig struct is enough,
 	// resources will be updated when the container is started again.
 	// If container is running (including paused), we need to update configs
 	// to the real world.

 	if container.IsRunning() && !container.IsRestarting() {

 		if err := daemon.containerd.UpdateResources(container.ID, toContainerdResources(hostConfig.Resources)); err != nil {

 			restoreConfig = true

 			// TODO: it would be nice if containerd responded with better errors here so we can classify this better.
 			return errCannotUpdate(container.ID, systemError{err})

 		}
 	}
 

 	daemon.LogContainerEvent(container, "update")
 

 	return nil
 }

 
 func errCannotUpdate(containerID string, err error) error {

 	return errors.Wrap(err, "Cannot update container "+containerID)

 }