deleting of blobs in shared directory behavior

Signed-off-by: Philippe Vlérick <[email protected]>

oci/layout/oci_delete.go

@@ -154,9 +154,20 @@ func (ref ociReference) getBlobsToDelete(blobsUsedByDescriptorToDelete map[diges
 	return blobsToDelete, nil
 }
 
+// This transport never generates layouts where blobs for an image are both in the local blobs directory
+// and the shared one; it’s either one or the other, depending on how OCISharedBlobDirPath is set.
+//
+// But we can’t correctly compute use counts for OCISharedBlobDirPath (because we don't know what
+// the other layouts sharing that directory are, and we might not even have permission to read them),
+// so we can’t really delete any blobs in that case.
+// Checking the _local_ blobs directory, and deleting blobs from there, doesn't really hurt,
+// in case the layout was created using some other tool or without OCISharedBlobDirPath set, so let's silently
+// check for local blobs (but we should make no noise if the blobs are actually in the shared directory).
+//
+// So, NOTE: the blobPath() call below hard-codes "" even in calls where OCISharedBlobDirPath is set
 func (ref ociReference) deleteBlobs(blobsToDelete *set.Set[digest.Digest]) error {
 	for _, digest := range blobsToDelete.Values() {
-		blobPath, err := ref.blobPath(digest, "") //Only delete in the local directory, not in the shared blobs path
+		blobPath, err := ref.blobPath(digest, "") //Only delete in the local directory, see comment above
 		if err != nil {
 			return err
 		}
@@ -173,13 +184,8 @@ func deleteBlob(blobPath string) error {
 	logrus.Debug(fmt.Sprintf("Deleting blob at %q", blobPath))
 
 	err := os.Remove(blobPath)
-	if err != nil {
-		if os.IsNotExist(err) {
-			logrus.Info(fmt.Sprintf("Blob at %q not found; it was either previously deleted or is in the shared blobs directory", blobPath))
-			return nil
-		} else {
-			return err
-		}
+	if err != nil && !os.IsNotExist(err) {
+		return err
 	} else {
 		return nil
 	}