From 692004c87b11845ebc4498f4c40ee905a32878c5 Mon Sep 17 00:00:00 2001
From: Solomon Hykes <solomon@dotcloud.com>
Date: Sat, 22 Jun 2013 12:29:42 -0700
Subject: [PATCH] Fix a bug which caused creation of empty images (and volumes)
 to crash. FIxes #995. Upstream-commit:
 290b1973a90e39f2b7f751f038633b9e6e4a1694 Component: engine

---
 components/engine/archive.go | 4 +++-
 components/engine/image.go   | 8 +++++---
 2 files changed, 8 insertions(+), 4 deletions(-)

diff --git a/components/engine/archive.go b/components/engine/archive.go
index 5756490bff..6ce1292bb6 100644
--- a/components/engine/archive.go
+++ b/components/engine/archive.go
@@ -108,7 +108,9 @@ func TarFilter(path string, compression Compression, filter []string) (io.Reader
 //  identity (uncompressed), gzip, bzip2, xz.
 // FIXME: specify behavior when target path exists vs. doesn't exist.
 func Untar(archive io.Reader, path string) error {
-
+	if archive == nil {
+		return fmt.Errorf("Empty archive")
+	}
 	bufferedArchive := bufio.NewReaderSize(archive, 10)
 	buf, err := bufferedArchive.Peek(10)
 	if err != nil {
diff --git a/components/engine/image.go b/components/engine/image.go
index cd76b8c432..bb6598b262 100644
--- a/components/engine/image.go
+++ b/components/engine/image.go
@@ -92,9 +92,11 @@ func StoreImage(img *Image, layerData Archive, root string, store bool) error {
 		defer file.Close()
 		layerData = file
 	}
-
-	if err := Untar(layerData, layer); err != nil {
-		return err
+	// If layerData is not nil, unpack it into the new layer
+	if layerData != nil {
+		if err := Untar(layerData, layer); err != nil {
+			return err
+		}
 	}
 
 	return StoreSize(img, root)