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|
{- git-annex command
-
- Copyright 2011 Joey Hess <joey@kitenet.net>
-
- Licensed under the GNU GPL version 3 or higher.
-}
module Command.Migrate where
import Control.Monad.State (liftIO)
import System.Posix.Files
import System.Directory
import Command
import qualified Annex
import qualified Backend
import Locations
import Types
import Content
import Messages
import qualified Command.Add
command :: [Command]
command = [Command "migrate" paramPath seek "switch data to different backend"]
seek :: [CommandSeek]
seek = [withBackendFilesInGit start]
start :: CommandStartBackendFile
start (file, b) = isAnnexed file $ \(key, oldbackend) -> do
exists <- inAnnex key
newbackend <- choosebackend b
if (newbackend /= oldbackend) && exists
then do
showStart "migrate" file
return $ Just $ perform file key newbackend
else
return Nothing
where
choosebackend Nothing = do
backends <- Backend.list
return $ head backends
choosebackend (Just backend) = return backend
perform :: FilePath -> Key -> Backend -> CommandPerform
perform file oldkey newbackend = do
g <- Annex.gitRepo
-- Store the old backend's cached key in the new backend
-- (the file can't be stored as usual, because it's already a symlink).
-- The old backend's key is not dropped from it, because there may
-- be other files still pointing at that key.
let src = annexLocation g oldkey
stored <- Backend.storeFileKey src $ Just newbackend
case stored of
Nothing -> return Nothing
Just (newkey, _) -> do
ok <- getViaTmp newkey $ \t -> do
-- Make a hard link to the old backend's
-- cached key, to avoid wasting disk space.
liftIO $ createLink src t
return True
if ok
then do
-- Update symlink to use the new key.
liftIO $ removeFile file
return $ Just $ Command.Add.cleanup file newkey
else return Nothing
|
