Add image.FromReference, replace most users of image.FromSource

This avoids some repetition, and (in all but one case) fixes
a missing .Close() on a failure path.

Signed-off-by: Miloslav Trmač <mitr@redhat.com>

directory/directory_transport.go

@@ -140,8 +140,7 @@ func (ref dirReference) PolicyConfigurationNamespaces() []string {
 // verify that UnparsedImage, and convert it into a real Image via image.FromUnparsedImage.
 // WARNING: This may not do the right thing for a manifest list, see image.FromSource for details.
 func (ref dirReference) NewImage(ctx context.Context, sys *types.SystemContext) (types.ImageCloser, error) {
-	src := newImageSource(ref)
-	return image.FromSource(ctx, sys, src)
+	return image.FromReference(ctx, sys, ref)
 }
 
 // NewImageSource returns a types.ImageSource for this reference.

docker/archive/transport.go

@@ -185,11 +185,7 @@ func (ref archiveReference) PolicyConfigurationNamespaces() []string {
 // verify that UnparsedImage, and convert it into a real Image via image.FromUnparsedImage.
 // WARNING: This may not do the right thing for a manifest list, see image.FromSource for details.
 func (ref archiveReference) NewImage(ctx context.Context, sys *types.SystemContext) (types.ImageCloser, error) {
-	src, err := newImageSource(ctx, sys, ref)
-	if err != nil {
-		return nil, err
-	}
-	return ctrImage.FromSource(ctx, sys, src)
+	return ctrImage.FromReference(ctx, sys, ref)
 }
 
 // NewImageSource returns a types.ImageSource for this reference.

docker/daemon/daemon_transport.go

@@ -195,11 +195,7 @@ func (ref daemonReference) PolicyConfigurationNamespaces() []string {
 // verify that UnparsedImage, and convert it into a real Image via image.FromUnparsedImage.
 // WARNING: This may not do the right thing for a manifest list, see image.FromSource for details.
 func (ref daemonReference) NewImage(ctx context.Context, sys *types.SystemContext) (types.ImageCloser, error) {
-	src, err := newImageSource(ctx, sys, ref)
-	if err != nil {
-		return nil, err
-	}
-	return image.FromSource(ctx, sys, src)
+	return image.FromReference(ctx, sys, ref)
 }
 
 // NewImageSource returns a types.ImageSource for this reference.

internal/image/sourced.go

@@ -9,6 +9,27 @@ import (
 	"github.com/containers/image/v5/types"
 )
 
+// FromReference returns a types.ImageCloser implementation for the default instance reading from reference.
+// If reference poitns to a manifest list, .Manifest() still returns the manifest list,
+// but other methods transparently return data from an appropriate image instance.
+//
+// The caller must call .Close() on the returned ImageCloser.
+//
+// NOTE: If any kind of signature verification should happen, build an UnparsedImage from the value returned by NewImageSource,
+// verify that UnparsedImage, and convert it into a real Image via image.FromUnparsedImage instead of calling this function.
+func FromReference(ctx context.Context, sys *types.SystemContext, ref types.ImageReference) (types.ImageCloser, error) {
+	src, err := ref.NewImageSource(ctx, sys)
+	if err != nil {
+		return nil, err
+	}
+	img, err := FromSource(ctx, sys, src)
+	if err != nil {
+		src.Close()
+		return nil, err
+	}
+	return img, nil
+}
+
 // imageCloser implements types.ImageCloser, perhaps allowing simple users
 // to use a single object without having keep a reference to a types.ImageSource
 // only to call types.ImageSource.Close().
@@ -31,6 +52,8 @@ type imageCloser struct {
 // NOTE: If any kind of signature verification should happen, build an UnparsedImage from the value returned by NewImageSource,
 // verify that UnparsedImage, and convert it into a real Image via image.FromUnparsedImage instead of calling this function.
 //
+// Most callers can use either FromUnparsedImage or FromReference instead.
+//
 // This is publicly visible as c/image/image.FromSource.
 func FromSource(ctx context.Context, sys *types.SystemContext, src types.ImageSource) (types.ImageCloser, error) {
 	img, err := FromUnparsedImage(ctx, sys, UnparsedInstance(src, nil))

oci/archive/oci_transport.go

@@ -122,11 +122,7 @@ func (ref ociArchiveReference) PolicyConfigurationNamespaces() []string {
 // verify that UnparsedImage, and convert it into a real Image via image.FromUnparsedImage.
 // WARNING: This may not do the right thing for a manifest list, see image.FromSource for details.
 func (ref ociArchiveReference) NewImage(ctx context.Context, sys *types.SystemContext) (types.ImageCloser, error) {
-	src, err := newImageSource(ctx, sys, ref)
-	if err != nil {
-		return nil, err
-	}
-	return image.FromSource(ctx, sys, src)
+	return image.FromReference(ctx, sys, ref)
 }
 
 // NewImageSource returns a types.ImageSource for this reference.

oci/layout/oci_transport.go

@@ -154,11 +154,7 @@ func (ref ociReference) PolicyConfigurationNamespaces() []string {
 // verify that UnparsedImage, and convert it into a real Image via image.FromUnparsedImage.
 // WARNING: This may not do the right thing for a manifest list, see image.FromSource for details.
 func (ref ociReference) NewImage(ctx context.Context, sys *types.SystemContext) (types.ImageCloser, error) {
-	src, err := newImageSource(sys, ref)
-	if err != nil {
-		return nil, err
-	}
-	return image.FromSource(ctx, sys, src)
+	return image.FromReference(ctx, sys, ref)
 }
 
 // getIndex returns a pointer to the index references by this ociReference. If an error occurs opening an index nil is returned together

openshift/openshift_transport.go

@@ -132,11 +132,7 @@ func (ref openshiftReference) PolicyConfigurationNamespaces() []string {
 // verify that UnparsedImage, and convert it into a real Image via image.FromUnparsedImage.
 // WARNING: This may not do the right thing for a manifest list, see image.FromSource for details.
 func (ref openshiftReference) NewImage(ctx context.Context, sys *types.SystemContext) (types.ImageCloser, error) {
-	src, err := newImageSource(sys, ref)
-	if err != nil {
-		return nil, err
-	}
-	return genericImage.FromSource(ctx, sys, src)
+	return genericImage.FromReference(ctx, sys, ref)
 }
 
 // NewImageSource returns a types.ImageSource for this reference.

ostree/ostree_transport.go

@@ -184,17 +184,7 @@ func (s *ostreeImageCloser) Size() (int64, error) {
 // NOTE: If any kind of signature verification should happen, build an UnparsedImage from the value returned by NewImageSource,
 // verify that UnparsedImage, and convert it into a real Image via image.FromUnparsedImage.
 func (ref ostreeReference) NewImage(ctx context.Context, sys *types.SystemContext) (types.ImageCloser, error) {
-	var tmpDir string
-	if sys == nil || sys.OSTreeTmpDirPath == "" {
-		tmpDir = os.TempDir()
-	} else {
-		tmpDir = sys.OSTreeTmpDirPath
-	}
-	src, err := newImageSource(tmpDir, ref)
-	if err != nil {
-		return nil, err
-	}
-	return image.FromSource(ctx, sys, src)
+	return image.FromReference(ctx, sys, ref)
 }
 
 // NewImageSource returns a types.ImageSource for this reference.

pkg/blobcache/blobcache.go

@@ -158,11 +158,7 @@ func (b *BlobCache) ClearCache() error {
 }
 
 func (b *BlobCache) NewImage(ctx context.Context, sys *types.SystemContext) (types.ImageCloser, error) {
-	src, err := b.NewImageSource(ctx, sys)
-	if err != nil {
-		return nil, errors.Wrapf(err, "error creating new image %q", transports.ImageName(b.reference))
-	}
-	return image.FromSource(ctx, sys, src)
+	return image.FromReference(ctx, sys, b)
 }
 
 func (b *BlobCache) NewImageSource(ctx context.Context, sys *types.SystemContext) (types.ImageSource, error) {

sif/transport.go

@@ -139,11 +139,7 @@ func (ref sifReference) PolicyConfigurationNamespaces() []string {
 // verify that UnparsedImage, and convert it into a real Image via image.FromUnparsedImage.
 // WARNING: This may not do the right thing for a manifest list, see image.FromSource for details.
 func (ref sifReference) NewImage(ctx context.Context, sys *types.SystemContext) (types.ImageCloser, error) {
-	src, err := newImageSource(ctx, sys, ref)
-	if err != nil {
-		return nil, err
-	}
-	return image.FromSource(ctx, sys, src)
+	return image.FromReference(ctx, sys, ref)
 }
 
 // NewImageSource returns a types.ImageSource for this reference.

tarball/tarball_reference.go

@@ -67,16 +67,7 @@ func (r *tarballReference) PolicyConfigurationNamespaces() []string {
 // verify that UnparsedImage, and convert it into a real Image via image.FromUnparsedImage.
 // WARNING: This may not do the right thing for a manifest list, see image.FromSource for details.
 func (r *tarballReference) NewImage(ctx context.Context, sys *types.SystemContext) (types.ImageCloser, error) {
-	src, err := r.NewImageSource(ctx, sys)
-	if err != nil {
-		return nil, err
-	}
-	img, err := image.FromSource(ctx, sys, src)
-	if err != nil {
-		src.Close()
-		return nil, err
-	}
-	return img, nil
+	return image.FromReference(ctx, sys, r)
 }
 
 func (r *tarballReference) DeleteImage(ctx context.Context, sys *types.SystemContext) error {