Method Apply

plugins/diff/erofs/differ.go:100–245

(ctx context.Context, desc ocispec.Descriptor, mounts []mount.Mount, opts ...diff.ApplyOpt)

}

func (s erofsDiff) Apply(ctx context.Context, desc ocispec.Descriptor, mounts []mount.Mount, opts ...diff.ApplyOpt) (d ocispec.Descriptor, err error) {
	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,
			}).Debugf("diff applied")
		}
	}()

	var (
		erofsLayerType string
		fastcopy       bool
	)
	diffLayerType := desc.MediaType
	native := erofsutils.IsErofsMediaType(diffLayerType)
	if native {
		base, ext, hasExt := strings.Cut(diffLayerType, "+")
		// Mimic the OCI layer for EROFS blobs for diff.NewProcessorChain(), so
		// there is no need to bother with too much unrelated logic for now.
		diffLayerType = ocispec.MediaTypeImageLayer
		if hasExt {
			// `+zstd` indicates that the original EROFS blob is additionally
			// compressed with standard zstd streams.
			// Only `+zstd` is considered since it is more performant than gzip
			// and has useful features like skippable frames.
			if ext != "zstd" {
				return emptyDesc, fmt.Errorf("unsupported erofs layer suffix: %s", ext)
			}
			diffLayerType = diffLayerType + "+zstd"
		} else {
			fastcopy = true
		}
		erofsLayerType = base
	} else if _, err := images.DiffCompression(ctx, diffLayerType); err != nil {
		return emptyDesc, fmt.Errorf("unsupported media type: %s", desc.MediaType)
	}

	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)
		}
	}

	layer, err := erofsutils.MountsToLayer(mounts)
	if err != nil {
		return emptyDesc, err
	}

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