Don't export whiteouts for single layers (#1629)

jonjohnsonjr · web-flow · commit 93be9c425318 · 2023-04-06T11:28:43.000-04:00
diff --git a/pkg/crane/export.go b/pkg/crane/export.go
@@ -30,16 +30,23 @@ func Export(img v1.Image, w io.Writer) error {
 		return err
 	}
 	if len(layers) == 1 {
-		// If it's a single layer, we don't have to flatten the filesystem.
-		// An added perk of skipping mutate.Extract here is that this works
-		// for non-tarball layers.
+		// If it's a single layer...
 		l := layers[0]
-		rc, err := l.Uncompressed()
+		mt, err := l.MediaType()
 		if err != nil {
 			return err
 		}
-		_, err = io.Copy(w, rc)
-		return err
+
+		if !mt.IsLayer() {
+			// ...and isn't an OCI mediaType, we don't have to flatten it.
+			// This lets export work for single layer, non-tarball images.
+			rc, err := l.Uncompressed()
+			if err != nil {
+				return err
+			}
+			_, err = io.Copy(w, rc)
+			return err
+		}
 	}
 	fs := mutate.Extract(img)
 	_, err = io.Copy(w, fs)
diff --git a/pkg/v1/types/types.go b/pkg/v1/types/types.go
@@ -88,3 +88,11 @@ func (m MediaType) IsSchema1() bool {
 	}
 	return false
 }
+
+func (m MediaType) IsLayer() bool {
+	switch m {
+	case DockerLayer, DockerUncompressedLayer, OCILayer, OCILayerZStd, OCIUncompressedLayer, DockerForeignLayer, OCIRestrictedLayer, OCIUncompressedRestrictedLayer:
+		return true
+	}
+	return false
+}

Original file line number	Diff line number	Diff line change
`@@ -88,3 +88,11 @@ func (m MediaType) IsSchema1() bool {`
`88`	`88`	`}`
`89`	`89`	`return false`
`90`	`90`	`}`
	`91`	`+`
	`92`	`+func (m MediaType) IsLayer() bool {`
	`93`	`+ switch m {`
	`94`	`+ case DockerLayer, DockerUncompressedLayer, OCILayer, OCILayerZStd, OCIUncompressedLayer, DockerForeignLayer, OCIRestrictedLayer, OCIUncompressedRestrictedLayer:`
	`95`	`+ return true`
	`96`	`+ }`
	`97`	`+ return false`
	`98`	`+}`