Function applyCIMLayerCommon

plugins/diff/windows/cimfs.go:254–311

applyCimFSCommon is a common function used for applying all diffs to a cim layer.

(ctx context.Context, desc ocispec.Descriptor, store content.Store, applyFunc cimApplyFunc, opts ...diff.ApplyOpt)

// applyCimFSCommon is a common function used for applying all diffs to a cim layer.
func applyCIMLayerCommon(ctx context.Context, desc ocispec.Descriptor, store content.Store, applyFunc cimApplyFunc, opts ...diff.ApplyOpt) (_ ocispec.Descriptor, err error) {
	var config diff.ApplyConfig
	for _, o := range opts {
		if err := o(ctx, desc, &config); err != nil {
			return emptyDesc, fmt.Errorf("failed to apply config opt: %w", err)
		}
	}

	t1 := time.Now()
	defer func() {
		if err == nil {
			log.G(ctx).WithFields(log.Fields{
				"d":      time.Since(t1),
				"digest": desc.Digest,
				"size":   desc.Size,
				"media":  desc.MediaType,
			}).Debug("diff applied")
		}
	}()

	ra, err := store.ReaderAt(ctx, desc)
	if err != nil {
		return emptyDesc, fmt.Errorf("failed to get reader from content store: %w", err)
	}
	defer ra.Close()

	processor := diff.NewProcessorChain(desc.MediaType, content.NewReader(ra))
	for {
		if processor, err = diff.GetProcessor(ctx, processor, config.ProcessorPayloads); err != nil {
			return emptyDesc, fmt.Errorf("failed to get stream processor for %s: %w", desc.MediaType, err)
		}
		if processor.MediaType() == ocispec.MediaTypeImageLayer {
			break
		}
	}
	defer processor.Close()

	digester := digest.Canonical.Digester()
	rc := &readCounter{
		r: io.TeeReader(processor, digester.Hash()),
	}

	if _, err = applyFunc(ctx, rc); err != nil {
		return emptyDesc, err
	}

	// Read any trailing data
	if _, err := io.Copy(io.Discard, rc); err != nil {
		return emptyDesc, err
	}

	return ocispec.Descriptor{
		MediaType: ocispec.MediaTypeImageLayer,
		Size:      rc.c,
		Digest:    digester.Digest(),
	}, nil

}