Read trailing data from tar reader

ambarve · ambarve · commit d3b817b95c39 · 2020-10-13T22:38:47.000-07:00
Not reading all the data from the tar reader causes the
layer digest mismatch which causes failures during unpack
of certain images for lcow. This changes fixes that.

Signed-off-by: Amit Barve &lt;ambarve@microsoft.com&gt;
diff --git a/diff/lcow/lcow.go b/diff/lcow/lcow.go
@@ -21,6 +21,7 @@ package lcow
 import (
 	"context"
 	"io"
+	"io/ioutil"
 	"os"
 	"path"
 	"time"
@@ -163,6 +164,11 @@ func (s windowsLcowDiff) Apply(ctx context.Context, desc ocispec.Descriptor, mou
 	}
 	outFile.Close()
 
+	// Read any trailing data
+	if _, err := io.Copy(ioutil.Discard, rc); err != nil {
+		return emptyDesc, err
+	}
+
 	err = security.GrantVmGroupAccess(layerPath)
 	if err != nil {
 		return emptyDesc, errors.Wrapf(err, "failed GrantVmGroupAccess on layer vhd: %v", layerPath)
