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