You are an expert in writing code in many different languages. Your goal is to perform code completion for the following code, keeping in mind the rest of the code and the file meta data.
    Metadata details:
    filename: overlay.go
    path of file: ./repos/podman/vendor/github.com/containers/storage/drivers/overlay
    
    the code of the file until where you have to start completion: //go:build linux
// +build linux

package overlay

import (
	"
    
func (d *Driver) getWhiteoutFormat() archive.WhiteoutFormat {
	whiteoutFormat := archive.OverlayWhiteoutFormat
	if d.options.mountProgram != "" {
		// If we are using a mount program, we are most likely running
		// as an unprivileged user that cannot use mknod, so fallback to the
		// AUFS whiteout format.
		whiteoutFormat = archive.AUFSWhiteoutFormat
	}
	return whiteoutFormat
}