Fix podman disk issue: use proper index for blank layers (#277)

Before, we were not dereferencing the index pointer when constructing the layer name,
resulting in layers named e.g., "blank_824644714416" when they should be "blank_0", "blank_1",
and so on.

Signed-off-by: Natalie Arellano <narellano@vmware.com>

local/store.go

@@ -217,10 +217,11 @@ func (s *Store) addImageToTar(tw *tar.Writer, image v1.Image, withName string) e
  blankIdx int
  )
  for _, layer := range layers {
- layerName, err := s.addLayerToTar(tw, layer, &blankIdx)
+ layerName, err := s.addLayerToTar(tw, layer, blankIdx)
  if err != nil {
  return err
  }
+ blankIdx++
  layerPaths = append(layerPaths, layerName)
  }
 
@@ -237,7 +238,7 @@ func (s *Store) addImageToTar(tw *tar.Writer, image v1.Image, withName string) e
  return addTextToTar(tw, manifestJSON, "manifest.json")
 }
 
-func (s *Store) addLayerToTar(tw *tar.Writer, layer v1.Layer, blankIdx *int) (string, error) {
+func (s *Store) addLayerToTar(tw *tar.Writer, layer v1.Layer, blankIdx int) (string, error) {
  // If the layer is a previous image layer that hasn't been downloaded yet,
  // cause ALL the previous image layers to be downloaded by grabbing the ReadCloser.
  layerReader, err := layer.Uncompressed()
@@ -253,7 +254,6 @@ func (s *Store) addLayerToTar(tw *tar.Writer, layer v1.Layer, blankIdx *int) (st
  }
  if size == -1 { // it's a base (always empty) layer
  layerName = fmt.Sprintf("blank_%d", blankIdx)
- *blankIdx++
  hdr := &tar.Header{Name: layerName, Mode: 0644, Size: 0}
  return layerName, tw.WriteHeader(hdr)
  }