nativeconverter.GetDiffID: support unpacked blobs

blobs without `containerd.io/uncompressed` labels were not supported

Signed-off-by: Akihiro Suda <[email protected]>

Author: AkihiroSuda

nativeconverter/nativeconverter.go

@@ -21,20 +21,20 @@ package nativeconverter
 
 import (
 	"bytes"
+	"compress/gzip"
 	"context"
 	"encoding/json"
 	"fmt"
+	"io"
 	"strings"
 	"sync"
 
 	"github.com/containerd/containerd"
 	"github.com/containerd/containerd/content"
-	"github.com/containerd/containerd/errdefs"
 	"github.com/containerd/containerd/images"
 	"github.com/containerd/containerd/platforms"
 	"github.com/opencontainers/go-digest"
 	ocispec "github.com/opencontainers/image-spec/specs-go/v1"
-	"github.com/pkg/errors"
 	"github.com/sirupsen/logrus"
 	"golang.org/x/sync/errgroup"
 )
@@ -566,9 +566,11 @@ func ConvertDockerMediaTypeToOCI(mt string) string {
 
 const LabelUncompressed = "containerd.io/uncompressed"
 
+// GetDiffID gets the diff ID of the layer blob descriptor.
 func GetDiffID(ctx context.Context, cs content.Store, desc ocispec.Descriptor) (digest.Digest, error) {
 	switch desc.MediaType {
 	case
+		// If the layer is already uncompressed, we can just return its digest
 		images.MediaTypeDockerSchema2Layer,
 		ocispec.MediaTypeImageLayer,
 		images.MediaTypeDockerSchema2LayerForeign,
@@ -580,11 +582,36 @@ func GetDiffID(ctx context.Context, cs content.Store, desc ocispec.Descriptor) (
 		return "", err
 	}
 	v, ok := info.Labels[LabelUncompressed]
-	if !ok {
-		return "", errors.Wrapf(errdefs.ErrNotFound, "content %s does not have label %q",
-			desc.Digest.String(), LabelUncompressed)
+	if ok {
+		// Fast path: if the image is already unpacked, we can use the label value
+		return digest.Parse(v)
 	}
-	return digest.Parse(v)
+	// if the image is not unpacked, we may not have the label
+	ra, err := cs.ReaderAt(ctx, desc)
+	if err != nil {
+		return "", err
+	}
+	defer ra.Close()
+	r := content.NewReader(ra)
+	gzR, err := gzip.NewReader(r)
+	if err != nil {
+		return "", err
+	}
+	digester := digest.Canonical.Digester()
+	hashW := digester.Hash()
+	if _, err := io.Copy(hashW, gzR); err != nil {
+		return "", err
+	}
+	if err := ra.Close(); err != nil {
+		return "", err
+	}
+	digest := digester.Digest()
+	// memorize the computed value
+	info.Labels[LabelUncompressed] = digest.String()
+	if _, err := cs.Update(ctx, info, "labels"); err != nil {
+		logrus.WithError(err).Warnf("failed to set %s label for %s", LabelUncompressed, desc.Digest)
+	}
+	return digest, nil
 }
 
 func ClearGCLabels(labels map[string]string, dgst digest.Digest) {