Finally, share a tarfile.Reader across archiveSource objects

In archive.Reader, embed a reference to tarfile.Reader to
the created ImageReference objects, and use them in NewImageSource.

Signed-off-by: Miloslav Trmač <[email protected]>

docker/archive/reader.go

@@ -49,14 +49,14 @@ func (r *Reader) List() ([][]types.ImageReference, error) {
 			if !ok {
 				return nil, errors.Errorf("Invalid tag %s (%s): does not contain a tag", tag, parsedTag.String())
 			}
-			ref, err := NewReference(r.path, nt)
+			ref, err := newReference(r.path, nt, -1, r.archive)
 			if err != nil {
 				return nil, errors.Wrapf(err, "Error creating a reference for tag %#v in manifest item @%d", tag, imageIndex)
 			}
 			refs = append(refs, ref)
 		}
 		if len(refs) == 0 {
-			ref, err := NewIndexReference(r.path, imageIndex)
+			ref, err := newReference(r.path, nil, imageIndex, r.archive)
 			if err != nil {
 				return nil, errors.Wrapf(err, "Error creating a reference for manifest item @%d", imageIndex)
 			}

docker/archive/src.go

@@ -15,11 +15,20 @@ type archiveImageSource struct {
 // newImageSource returns a types.ImageSource for the specified image reference.
 // The caller must call .Close() on the returned ImageSource.
 func newImageSource(ctx context.Context, sys *types.SystemContext, ref archiveReference) (types.ImageSource, error) {
-	archive, err := tarfile.NewReaderFromFile(sys, ref.path)
-	if err != nil {
-		return nil, err
+	var archive *tarfile.Reader
+	var closeArchive bool
+	if ref.archiveReader != nil {
+		archive = ref.archiveReader
+		closeArchive = false
+	} else {
+		a, err := tarfile.NewReaderFromFile(sys, ref.path)
+		if err != nil {
+			return nil, err
+		}
+		archive = a
+		closeArchive = true
 	}
-	src := tarfile.NewSource(archive, true, ref.ref, ref.sourceIndex)
+	src := tarfile.NewSource(archive, closeArchive, ref.ref, ref.sourceIndex)
 	return &archiveImageSource{
 		Source: src,
 		ref:    ref,

docker/archive/transport.go

@@ -6,6 +6,7 @@ import (
 	"strconv"
 	"strings"
 
+	"github.com/containers/image/v5/docker/internal/tarfile"
 	"github.com/containers/image/v5/docker/reference"
 	ctrImage "github.com/containers/image/v5/image"
 	"github.com/containers/image/v5/transports"
@@ -48,6 +49,9 @@ type archiveReference struct {
 	// If not -1, a zero-based index of the image in the manifest. Valid only for sources.
 	// Must not be set if ref is set.
 	sourceIndex int
+	// If not nil, must have been created from path (but archiveReader.path may point at a temporary
+	// file, not necesarily path precisely).
+	archiveReader *tarfile.Reader
 }
 
 // ParseReference converts a string, which should not start with the ImageTransport.Name prefix, into an Docker ImageReference.
@@ -86,21 +90,23 @@ func ParseReference(refString string) (types.ImageReference, error) {
 		}
 	}
 
-	return newReference(path, nt, sourceIndex)
+	return newReference(path, nt, sourceIndex, nil)
 }
 
 // NewReference returns a Docker archive reference for a path and an optional reference.
 func NewReference(path string, ref reference.NamedTagged) (types.ImageReference, error) {
-	return newReference(path, ref, -1)
+	return newReference(path, ref, -1, nil)
 }
 
 // NewIndexReference returns a Docker archive reference for a path and a zero-based source manifest index.
 func NewIndexReference(path string, sourceIndex int) (types.ImageReference, error) {
-	return newReference(path, nil, sourceIndex)
+	return newReference(path, nil, sourceIndex, nil)
 }
 
-// newReference returns a docker archive reference for a path and an optional reference or sourceIndex.
-func newReference(path string, ref reference.NamedTagged, sourceIndex int) (types.ImageReference, error) {
+// newReference returns a docker archive reference for a path, an optional reference or sourceIndex,
+// and optionally a tarfile.Reader matching path.
+func newReference(path string, ref reference.NamedTagged, sourceIndex int,
+	archiveReader *tarfile.Reader) (types.ImageReference, error) {
 	if strings.Contains(path, ":") {
 		return nil, errors.Errorf("Invalid docker-archive: reference: colon in path %q is not supported", path)
 	}
@@ -114,9 +120,10 @@ func newReference(path string, ref reference.NamedTagged, sourceIndex int) (type
 		return nil, errors.Errorf("Invalid docker-archive: reference: index @%d must not be negative", sourceIndex)
 	}
 	return archiveReference{
-		path:        path,
-		ref:         ref,
-		sourceIndex: sourceIndex,
+		path:          path,
+		ref:           ref,
+		sourceIndex:   sourceIndex,
+		archiveReader: archiveReader,
 	}, nil
 }
 

docker/archive/transport_test.go

@@ -134,7 +134,7 @@ func TestNewReference(t *testing.T) {
 
 	// Complete coverage testing of the private newReference here as well
 	ntRef := namedTaggedRef(t, "busybox:latest")
-	_, err = newReference("path", ntRef, 0)
+	_, err = newReference("path", ntRef, 0, nil)
 	assert.Error(t, err)
 }