func flush(r io.Reader) (bytes int64, err error) {
	return io.Copy(ioutil.Discard, r)
}
flush consumes all the bytes from the reader discarding
any errors
package chrootarchive
import (
	"fmt"
	"io"
	"io/ioutil"
	"os"
	"github.com/docker/docker/pkg/reexec"
)
func init() {
	reexec.Register("docker-applyLayer", applyLayer)
	reexec.Register("docker-untar", untar)
}
func fatal(err error) {
	fmt.Fprint(os.Stderr, err)
	os.Exit(1)
}