Method Unpack

core/unpack/unpacker.go:196–272

Unpack wraps an image handler to filter out blob handling and scheduling them during the unpack process. When an image config is encountered, the unpack process will be started in a goroutine.

(h images.Handler)

// during the unpack process. When an image config is encountered, the unpack
// process will be started in a goroutine.
func (u *Unpacker) Unpack(h images.Handler) images.Handler {
	var (
		lock   sync.Mutex
		layers = map[digest.Digest][]ocispec.Descriptor{}
	)

	var layerTypes map[string]bool
	var configTypes map[string]bool
	for _, p := range u.platforms {
		if p.ConfigType != "" {
			if configTypes == nil {
				configTypes = make(map[string]bool)
			}
			configTypes[p.ConfigType] = true
		}
		if len(p.LayerTypes) > 0 {
			if layerTypes == nil {
				layerTypes = make(map[string]bool)
			}
			for _, t := range p.LayerTypes {
				layerTypes[t] = true
			}
		}
	}

	return images.HandlerFunc(func(ctx context.Context, desc ocispec.Descriptor) ([]ocispec.Descriptor, error) {
		ctx, span := tracing.StartSpan(ctx, tracing.Name(unpackSpanPrefix, "UnpackHandler"))
		defer span.End()
		span.SetAttributes(
			tracing.Attribute("descriptor.media.type", desc.MediaType),
			tracing.Attribute("descriptor.digest", desc.Digest.String()))
		unlock, err := u.lockBlobDescriptor(ctx, desc)
		if err != nil {
			return nil, err
		}
		children, err := h.Handle(ctx, desc)
		unlock()
		if err != nil {
			return children, err
		}

		if images.IsManifestType(desc.MediaType) {
			var nonLayers []ocispec.Descriptor
			var manifestLayers []ocispec.Descriptor
			// Split layers from non-layers, layers will be handled after
			// the config
			for i, child := range children {
				span.SetAttributes(
					tracing.Attribute("descriptor.child."+strconv.Itoa(i), []string{child.MediaType, child.Digest.String()}),
				)
				if images.IsLayerType(child.MediaType) || layerTypes[child.MediaType] {
					manifestLayers = append(manifestLayers, child)
				} else {
					nonLayers = append(nonLayers, child)
				}
			}

			lock.Lock()