From 2eb5cfb7adf34ae61a9b1b564c8ff0e8da06e14b Mon Sep 17 00:00:00 2001
From: Nick Craig-Wood <nick@craig-wood.com>
Date: Wed, 31 Jan 2018 14:22:49 +0000
Subject: [PATCH] fs: Formalize the ObjectUnWrapper interface

---
 backend/crypt/crypt.go | 25 +++++++++++++------------
 fs/fs.go               |  7 +++++++
 2 files changed, 20 insertions(+), 12 deletions(-)

diff --git a/backend/crypt/crypt.go b/backend/crypt/crypt.go
index 63ce31221..f62ce9731 100644
--- a/backend/crypt/crypt.go
+++ b/backend/crypt/crypt.go
@@ -662,16 +662,17 @@ func (o *ObjectInfo) Hash(hash hash.Type) (string, error) {
 
 // Check the interfaces are satisfied
 var (
-	_ fs.Fs             = (*Fs)(nil)
-	_ fs.Purger         = (*Fs)(nil)
-	_ fs.Copier         = (*Fs)(nil)
-	_ fs.Mover          = (*Fs)(nil)
-	_ fs.DirMover       = (*Fs)(nil)
-	_ fs.PutUncheckeder = (*Fs)(nil)
-	_ fs.PutStreamer    = (*Fs)(nil)
-	_ fs.CleanUpper     = (*Fs)(nil)
-	_ fs.UnWrapper      = (*Fs)(nil)
-	_ fs.ListRer        = (*Fs)(nil)
-	_ fs.ObjectInfo     = (*ObjectInfo)(nil)
-	_ fs.Object         = (*Object)(nil)
+	_ fs.Fs              = (*Fs)(nil)
+	_ fs.Purger          = (*Fs)(nil)
+	_ fs.Copier          = (*Fs)(nil)
+	_ fs.Mover           = (*Fs)(nil)
+	_ fs.DirMover        = (*Fs)(nil)
+	_ fs.PutUncheckeder  = (*Fs)(nil)
+	_ fs.PutStreamer     = (*Fs)(nil)
+	_ fs.CleanUpper      = (*Fs)(nil)
+	_ fs.UnWrapper       = (*Fs)(nil)
+	_ fs.ListRer         = (*Fs)(nil)
+	_ fs.ObjectInfo      = (*ObjectInfo)(nil)
+	_ fs.Object          = (*Object)(nil)
+	_ fs.ObjectUnWrapper = (*Object)(nil)
 )
diff --git a/fs/fs.go b/fs/fs.go
index b743ffb94..6109cddf5 100644
--- a/fs/fs.go
+++ b/fs/fs.go
@@ -237,6 +237,13 @@ type MimeTyper interface {
 	MimeType() string
 }
 
+// ObjectUnWrapper is an optional interface for Object
+type ObjectUnWrapper interface {
+	// UnWrap returns the Object that this Object is wrapping or
+	// nil if it isn't wrapping anything
+	UnWrap() Object
+}
+
 // ListRCallback defines a callback function for ListR to use
 //
 // It is called for each tranche of entries read from the listing and