1 files changed, 56 insertions, 0 deletions
diff --git a/libpod/diff.go b/libpod/diff.go
index f348e6b81..925bda927 100644
--- a/libpod/diff.go
+++ b/libpod/diff.go
@@ -1,6 +1,9 @@
 package libpod
 
 import (
+	"archive/tar"
+	"io"
+
 	"github.com/containers/libpod/libpod/layers"
 	"github.com/containers/storage/pkg/archive"
 	"github.com/pkg/errors"
@@ -44,6 +47,59 @@ func (r *Runtime) GetDiff(from, to string) ([]archive.Change, error) {
 	return rchanges, err
 }
 
+// skipFileInTarAchive is an archive.TarModifierFunc function
+// which tells archive.ReplaceFileTarWrapper to skip files
+// from the tarstream
+func skipFileInTarAchive(path string, header *tar.Header, content io.Reader) (*tar.Header, []byte, error) {
+	return nil, nil, nil
+}
+
+// GetDiffTarStream returns the differences between the two images, layers, or containers.
+// It is the same functionality as GetDiff() except that it returns a tarstream
+func (r *Runtime) GetDiffTarStream(from, to string) (io.ReadCloser, error) {
+	toLayer, err := r.getLayerID(to)
+	if err != nil {
+		return nil, err
+	}
+	fromLayer := ""
+	if from != "" {
+		fromLayer, err = r.getLayerID(from)
+		if err != nil {
+			return nil, err
+		}
+	}
+	rc, err := r.store.Diff(fromLayer, toLayer, nil)
+	if err != nil {
+		return nil, err
+	}
+
+	// Skip files in the tar archive which are listed
+	// in containerMounts map. Just as in the GetDiff()
+	// function from above
+	filterMap := make(map[string]archive.TarModifierFunc)
+	for key := range containerMounts {
+		filterMap[key[1:]] = skipFileInTarAchive
+		// In the tarstream directories always include a trailing '/'.
+		// For simplicity this duplicates every entry from
+		// containerMounts with a trailing '/', as containerMounts
+		// does not use trailing '/' for directories.
+		filterMap[key[1:]+"/"] = skipFileInTarAchive
+	}
+
+	filteredTarStream := archive.ReplaceFileTarWrapper(rc, filterMap)
+	return filteredTarStream, nil
+}
+
+// ApplyDiffTarStream applies the changes stored in 'diff' to the layer 'to'
+func (r *Runtime) ApplyDiffTarStream(to string, diff io.Reader) error {
+	toLayer, err := r.getLayerID(to)
+	if err != nil {
+		return err
+	}
+	_, err = r.store.ApplyDiff(toLayer, diff)
+	return err
+}
+
 // GetLayerID gets a full layer id given a full or partial id
 // If the id matches a container or image, the id of the top layer is returned
 // If the id matches a layer, the top layer id is returned