// fixManifestLayers removes repeated layers from the manifest and checks the
// correctness of the parent chain.
func fixManifestLayers(m *manifest.Manifest) error {
images := make([]*image.Image, len(m.FSLayers))
for i := range m.FSLayers {
img, err := image.NewImgJSON([]byte(m.History[i].V1Compatibility))
if err != nil {
return err
}
images[i] = img
if err := image.ValidateID(img.ID); err != nil {
return err
}
}
if images[len(images)-1].Parent != "" {
return errors.New("Invalid parent ID in the base layer of the image.")
}
// check general duplicates to error instead of a deadlock
idmap := make(map[string]struct{})
var lastID string
for _, img := range images {
// skip IDs that appear after each other, we handle those later
if _, exists := idmap[img.ID]; img.ID != lastID && exists {
return fmt.Errorf("ID %+v appears multiple times in manifest", img.ID)
}
lastID = img.ID
idmap[lastID] = struct{}{}
}
// backwards loop so that we keep the remaining indexes after removing items
for i := len(images) - 2; i >= 0; i-- {
if images[i].ID == images[i+1].ID { // repeated ID. remove and continue
m.FSLayers = append(m.FSLayers[:i], m.FSLayers[i+1:]...)
m.History = append(m.History[:i], m.History[i+1:]...)
} else if images[i].Parent != images[i+1].ID {
return fmt.Errorf("Invalid parent ID. Expected %v, got %v.", images[i+1].ID, images[i].Parent)
}
}
return nil
}