package daemon
 
 import (
 	"fmt"
 

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

 )
 

 // ContainerUpdate updates configuration of the container

 func (daemon *Daemon) ContainerUpdate(name string, hostConfig *container.HostConfig, validateHostname bool) ([]string, error) {

 	var warnings []string
 

 	warnings, err := daemon.verifyContainerSettings(hostConfig, nil, true, validateHostname)

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

 // ContainerUpdateCmdOnBuild updates Path and Args for the container with ID cID.
 func (daemon *Daemon) ContainerUpdateCmdOnBuild(cID string, cmd []string) error {

 	if len(cmd) == 0 {
 		return nil
 	}

 	c, err := daemon.GetContainer(cID)
 	if err != nil {
 		return err
 	}
 	c.Path = cmd[0]
 	c.Args = cmd[1:]
 	return 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.ToDisk()
 			container.Unlock()
 		}
 	}()
 

 	if container.RemovalInProgress || container.Dead {

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

 	}
 
 	if container.IsRunning() && hostConfig.KernelMemory != 0 {

 		return errCannotUpdate(container.ID, fmt.Errorf("Can not update kernel memory to a running container, please stop it first."))

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

 		restoreConfig = true

 		return errCannotUpdate(container.ID, err)

 	}
 

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

 			return errCannotUpdate(container.ID, err)

 		}
 	}
 

 	daemon.LogContainerEvent(container, "update")
 

 	return nil
 }

 
 func errCannotUpdate(containerID string, err error) error {
 	return fmt.Errorf("Cannot update container %s: %v", containerID, err)
 }