rekey: New plumbing level command, can be used to change the keys used for files en masse.

Command/Migrate.hs

@@ -58,22 +58,27 @@ perform file oldkey newbackend = do
 	cleantmp tmpfile
 	case k of
 		Nothing -> stop
-		Just (newkey, _) -> stopUnless (link src newkey) $ do
-			-- Update symlink to use the new key.
-			liftIO $ removeFile file
-
-			-- If the old key had some
-			-- associated urls, record them for
-			-- the new key as well.
-			urls <- getUrls oldkey
-			unless (null urls) $
-				mapM_ (setUrlPresent newkey) urls
-
-			next $ Command.Add.cleanup file newkey True
+		Just (newkey, _) -> stopUnless (linkKey src newkey) $
+			next $ cleanup file oldkey newkey
 	where
 		cleantmp t = liftIO $ whenM (doesFileExist t) $ removeFile t
-		link src newkey = getViaTmpUnchecked newkey $ \t -> do
-			-- Make a hard link to the old backend's
-			-- cached key, to avoid wasting disk space.
-			liftIO $ unlessM (doesFileExist t) $ createLink src t
-			return True	
+
+linkKey :: FilePath -> Key -> Annex Bool
+linkKey src newkey = getViaTmpUnchecked newkey $ \t -> do
+	-- Make a hard link to the old backend's
+	-- cached key, to avoid wasting disk space.
+	liftIO $ unlessM (doesFileExist t) $ createLink src t
+	return True
+
+cleanup :: FilePath -> Key -> Key -> CommandCleanup
+cleanup file oldkey newkey = do
+	-- Update symlink to use the new key.
+	liftIO $ removeFile file
+
+	-- If the old key had some associated urls, record them for
+	-- the new key as well.
+	urls <- getUrls oldkey
+	unless (null urls) $
+		mapM_ (setUrlPresent newkey) urls
+
+	Command.Add.cleanup file newkey True

Command/ReKey.hs

@@ -0,0 +1,46 @@
+{- git-annex command
+ -
+ - Copyright 2012 Joey Hess <joey@kitenet.net>
+ -
+ - Licensed under the GNU GPL version 3 or higher.
+ -}
+
+module Command.ReKey where
+
+import Common.Annex
+import Command
+import qualified Annex
+import Types.Key
+import Annex.Content
+import qualified Command.Migrate
+
+def :: [Command]
+def = [command "rekey"
+	(paramOptional $ paramRepeating $ paramPair paramPath paramKey)
+	seek "change keys used for files"]
+
+seek :: [CommandSeek]
+seek = [withPairs start]
+
+start :: (FilePath, String) -> CommandStart
+start (file, keyname) = ifAnnexed file go stop
+	where
+		newkey = fromMaybe (error "bad key") $ readKey keyname
+		go (oldkey, _)
+			| oldkey == newkey = stop
+			| otherwise = do
+				showStart "rekey" file
+				next $ perform file oldkey newkey
+
+perform :: FilePath -> Key -> Key -> CommandPerform
+perform file oldkey newkey = do
+	present <- inAnnex oldkey
+	_ <- if present
+		then do
+			src <- inRepo $ gitAnnexLocation oldkey
+			Command.Migrate.linkKey src newkey
+		else do
+			unlessM (Annex.getState Annex.force) $
+				error $ file ++ " is not available (use --force to override)"
+			return True
+	next $ Command.Migrate.cleanup file oldkey newkey

GitAnnex.hs

@@ -28,6 +28,7 @@ import qualified Command.Copy
 import qualified Command.Get
 import qualified Command.FromKey
 import qualified Command.DropKey
+import qualified Command.ReKey
 import qualified Command.Reinject
 import qualified Command.Fix
 import qualified Command.Init
@@ -80,6 +81,7 @@ cmds = concat
 	, Command.Dead.def
 	, Command.FromKey.def
 	, Command.DropKey.def
+	, Command.ReKey.def
 	, Command.Fix.def
 	, Command.Fsck.def
 	, Command.Unused.def

Seek.hs

@@ -45,6 +45,13 @@ withWords a params = return [a params]
 withStrings :: (String -> CommandStart) -> CommandSeek
 withStrings a params = return $ map a params
 
+withPairs :: ((String, String) -> CommandStart) -> CommandSeek
+withPairs a params = return $ map a $ pairs [] params
+	where
+		pairs c [] = reverse c
+		pairs c (x:y:xs) = pairs ((x,y):c) xs
+		pairs _ _ = error "expected pairs"
+
 withFilesToBeCommitted :: (String -> CommandStart) -> CommandSeek
 withFilesToBeCommitted a params = prepFiltered a $
 	seekHelper LsFiles.stagedNotDeleted params

debian/changelog

@@ -30,6 +30,8 @@ git-annex (3.20120124) UNRELEASED; urgency=low
     location of the file.
   * addurl: Normalize badly encoded urls.
   * addurl: Add --pathdepth option.
+  * rekey: New plumbing level command, can be used to change the keys used
+    for files en masse.
 
  -- Joey Hess <joeyh@debian.org>  Tue, 24 Jan 2012 16:21:55 -0400
 

doc/git-annex.mdwn

@@ -399,6 +399,14 @@ subdirectories).
 
 	git annex dropkey SHA1-s10-7da006579dd64330eb2456001fd01948430572f2
 
+* rekey [file key ...]
+  
+  This plumbing-level command is similar to migrate, but you specify
+  both the file, and the new key to use for it.
+
+  With --force, even files whose content is not currently available will
+  be rekeyed. Use with caution.
+
 # OPTIONS
 
 * --force