const (
	FsMagicBtrfs = FsMagic(0x9123683E)
	FsMagicAufs  = FsMagic(0x61756673)
)

var (
	DefaultDriver string

	ErrNotSupported   = errors.New("driver not supported")
	ErrPrerequisites  = errors.New("prerequisites for driver not satisfied (wrong filesystem?)")
	ErrIncompatibleFS = fmt.Errorf("backing file system is unsupported for this graph driver")
)

type Differ interface {
	Diff(id string) (archive.Archive, error)
	Changes(id string) ([]archive.Change, error)
	ApplyDiff(id string, diff archive.ArchiveReader) error
	DiffSize(id string) (bytes int64, err error)
}

type Driver interface {
	String() string

	Create(id, parent string) error
	Remove(id string) error

	Get(id, mountLabel string) (dir string, err error)
	Put(id string)
	Exists(id string) bool

	Status() [][2]string

	Cleanup() error
}

type FsMagic uint64

type InitFunc func(root string, options []string) (Driver, error)