How to make chown of dir not been root when use api CopyToContainer

Description
How to make chown of dir not been root when use api CopyToContainer to copy files to container. I set user as common in dockerdile and use api start container. File's own is correct, but dir's own is root. It make me confuse. How can it create a root dir in commom user.

Here is my code

// CopyTo copy files to container.
func (m *Manager) CopyTo(files map[string][]byte, fileMode int64, options types.CopyToContainerOptions) error {
	buffer := bytes.NewBuffer(nil)
	gWriter := gzip.NewWriter(buffer)
	tWriter := tar.NewWriter(gWriter)
	for path, file := range files {
		var zeroTime time.Time
		if err := tWriter.WriteHeader(&tar.Header{
			Name:       path,
			Size:       int64(len(file)),
			ModTime:    zeroTime,
			AccessTime: zeroTime,
			ChangeTime: zeroTime,
			Mode:       fileMode,
			Uid:        usrUID,
			Gid:        usrGID,
		}); err != nil {
			return err
		}
		if _, err := tWriter.Write(file); err != nil {
			return err
		}
	}
	if err := gWriter.Close(); err != nil {
		return err
	}
	if err := gWriter.Close(); err != nil {
		return err
	}
	return m.Cli.CopyToContainer(*m.Ctx, m.ID, "/", bytes.NewBuffer(buffer.Bytes()), options)
}

Describe the results you received:
File's own is pass and dir' own is root.

Describe the results you expected:
Both own of file and dir is pass.

Additional information you deem important (e.g. issue happens only occasionally):

Output of docker version:
here is my go mod

replace (
	github.com/docker/docker => github.com/moby/moby v0.0.0-20181106193140-f5749085e9cb // v18.09.0
)
require (
	github.com/docker/docker v1.13.1
)

Start by reproducing the behavior through the docker client CopyToContainer API using the supplied Go example, then inspect how its tar archive handles file and directory entries, including Uid and Gid. Compare ownership for both entries when the container runs as the non-root user; done means determining whether the reported directory ownership matches the API's documented behavior and identifying the relevant fix or documentation gap.