Function convertRootfsToOCIArchive

pkg/cmd/image/import.go:154–197

(ctx context.Context, client *containerd.Client, r io.ReadCloser, options types.ImageImportOptions, prefix string)

}

func convertRootfsToOCIArchive(ctx context.Context, client *containerd.Client, r io.ReadCloser, options types.ImageImportOptions, prefix string) (io.ReadCloser, error) {
	defer r.Close()

	ctx, done, err := client.WithLease(ctx, leases.WithRandomID(), leases.WithExpiration(1*time.Hour))
	if err != nil {
		return nil, err
	}
	defer done(ctx)

	decomp, err := compression.DecompressStream(r)
	if err != nil {
		return nil, err
	}
	defer decomp.Close()

	cs := client.ContentStore()
	ref := randomRef("import-layer-")
	w, err := content.OpenWriter(ctx, cs, content.WithRef(ref))
	if err != nil {
		return nil, err
	}
	defer w.Close()

	if err := w.Truncate(0); err != nil {
		return nil, err
	}

	layerDigest, diffID, layerSize, err := compressAndWriteLayer(ctx, w, decomp)
	if err != nil {
		return nil, err
	}

	imgConfig, configDigest, err := buildImageConfig(diffID, options)
	if err != nil {
		return nil, err
	}

	layerContent, err := readLayerContent(ctx, cs, layerDigest, layerSize)
	if err != nil {
		return nil, err
	}

	return buildDockerArchive(imgConfig, configDigest, layerContent, layerDigest, prefix)
}

func compressAndWriteLayer(ctx context.Context, w content.Writer, r io.Reader) (digest.Digest, digest.Digest, int64, error) {
	digester := digest.Canonical.Digester()