From 4c53da8f9a18a228c6c209b9a80003f0d164822a Mon Sep 17 00:00:00 2001
From: Tonis Tiigi <tonistiigi@gmail.com>
Date: Mon, 21 Sep 2015 14:36:35 -0700
Subject: [PATCH] Add basic support for .wh..wh..opq
MIME-Version: 1.0
Content-Type: text/plain; charset=UTF-8
Content-Transfer-Encoding: 8bit

This fixes the case where directory is removed in
aufs and then the same layer is imported to a
different graphdriver.

Currently when you do `rm -rf /foo && mkdir /foo`
in a layer in aufs the files under `foo` would
only be be hidden on aufs.

The problems with this fix:

1) When a new diff is recreated from non-aufs driver
the `opq` files would not be there. This should not
mean layer differences for the user but still
different content in the tar (one would have one
`opq` file, the others would have `.wh.*` for every
file inside that folder). This difference also only
happens if the tar-split file isn’t stored for the
layer.

2) New files that have the filenames before `.wh..wh..opq`
when they are sorted do not get picked up by non-aufs
graphdrivers. Fixing this would require a bigger
refactoring that is planned in the future.


Signed-off-by: Tonis Tiigi <tonistiigi@gmail.com>
---
 archive/diff.go | 25 +++++++++++++++++++++----
 1 file changed, 21 insertions(+), 4 deletions(-)

diff --git a/archive/diff.go b/archive/diff.go
index 50656cb..c343d8a 100644
--- a/archive/diff.go
+++ b/archive/diff.go
@@ -100,7 +100,10 @@ func UnpackLayer(dest string, layer Reader) (size int64, err error) {
 					return 0, err
 				}
 			}
-			continue
+
+			if hdr.Name != ".wh..wh..opq" {
+				continue
+			}
 		}
 		path := filepath.Join(dest, hdr.Name)
 		rel, err := filepath.Rel(dest, path)
@@ -116,9 +119,23 @@ func UnpackLayer(dest string, layer Reader) (size int64, err error) {
 
 		if strings.HasPrefix(base, ".wh.") {
 			originalBase := base[len(".wh."):]
-			originalPath := filepath.Join(filepath.Dir(path), originalBase)
-			if err := os.RemoveAll(originalPath); err != nil {
-				return 0, err
+			dir := filepath.Dir(path)
+			if originalBase == ".wh..opq" {
+				fi, err := os.Lstat(dir)
+				if err != nil && !os.IsNotExist(err) {
+					return 0, err
+				}
+				if err := os.RemoveAll(dir); err != nil {
+					return 0, err
+				}
+				if err := os.Mkdir(dir, fi.Mode()&os.ModePerm); err != nil {
+					return 0, err
+				}
+			} else {
+				originalPath := filepath.Join(dir, originalBase)
+				if err := os.RemoveAll(originalPath); err != nil {
+					return 0, err
+				}
 			}
 		} else {
 			// If path exits we almost always just want to remove and replace it.