// TarLayer returns a tar archive of the image's filesystem layer.
func (img *Image) TarLayer() (arch archive.Archive, err error) {
if img.graph == nil {
return nil, fmt.Errorf("Can't load storage driver for unregistered image %s", img.ID)
}
driver := img.graph.driver
if differ, ok := driver.(graphdriver.Differ); ok {
return differ.Diff(img.ID)
}
imgFs, err := driver.Get(img.ID)
if err != nil {
return nil, err
}
defer func() {
if err == nil {
driver.Put(img.ID)
}
}()
if img.Parent == "" {
archive, err := archive.Tar(imgFs, archive.Uncompressed)
if err != nil {
return nil, err
}
return EofReader(archive, func() { driver.Put(img.ID) }), nil
}
parentFs, err := driver.Get(img.Parent)
if err != nil {
return nil, err
}
defer driver.Put(img.Parent)
changes, err := archive.ChangesDirs(imgFs, parentFs)
if err != nil {
return nil, err
}
archive, err := archive.ExportChanges(imgFs, changes)
if err != nil {
return nil, err
}
return EofReader(archive, func() { driver.Put(img.ID) }), nil
}
func (runtime *Runtime) Diff(container *Container) (archive.Archive, error) {
if differ, ok := runtime.driver.(graphdriver.Differ); ok {
return differ.Diff(container.ID)
}
changes, err := runtime.Changes(container)
if err != nil {
return nil, err
}
cDir, err := runtime.driver.Get(container.ID)
if err != nil {
return nil, fmt.Errorf("Error getting container rootfs %s from driver %s: %s", container.ID, container.runtime.driver, err)
}
archive, err := archive.ExportChanges(cDir, changes)
if err != nil {
return nil, err
}
return EofReader(archive, func() { runtime.driver.Put(container.ID) }), nil
}