code: func (daemon *Daemon) ContainerArchivePath(name string, path string) (content io.ReadCloser, stat *types.ContainerPathStat, err error) {
  	container, err := daemon.GetContainer(name)
  	if err != nil {
  		return nil, nil, err
  	}
  
  	// Make sure an online file-system operation is permitted.
  	if err := daemon.isOnlineFSOperationPermitted(container); err != nil {
  		return nil, nil, errdefs.System(err)
  	}
  
  	content, stat, err = daemon.containerArchivePath(container, path)
  	if err == nil {
  		return content, stat, nil
  	}
  
  	if os.IsNotExist(err) {
  		return nil, nil, containerFileNotFound{path, name}
  	}
  	return nil, nil, errdefs.System(err)
  }
docs: // ContainerArchivePath creates an archive of the filesystem resource at the
  // specified path in the container identified by the given name. Returns a
  // tar archive of the resource and whether it was a directory or a single file.