113 lines
3.3 KiB
Haskell
113 lines
3.3 KiB
Haskell
{- git-annex key/value backends
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-
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- Copyright 2010 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 Backend (
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list,
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orderedList,
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genKey,
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lookupFile,
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chooseBackend,
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lookupBackendName,
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maybeLookupBackendName
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) where
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import System.Posix.Files
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import Common.Annex
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import Config
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import qualified Annex
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import Annex.CheckAttr
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import Types.Key
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import qualified Types.Backend as B
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-- When adding a new backend, import it here and add it to the list.
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import qualified Backend.SHA
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import qualified Backend.WORM
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import qualified Backend.URL
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list :: [Backend]
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list = Backend.SHA.backends ++ Backend.WORM.backends ++ Backend.URL.backends
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{- List of backends in the order to try them when storing a new key. -}
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orderedList :: Annex [Backend]
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orderedList = do
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l <- Annex.getState Annex.backends -- list is cached here
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if not $ null l
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then return l
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else handle =<< Annex.getState Annex.forcebackend
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where
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handle Nothing = standard
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handle (Just "") = standard
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handle (Just name) = do
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l' <- (lookupBackendName name :) <$> standard
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Annex.changeState $ \s -> s { Annex.backends = l' }
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return l'
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standard = parseBackendList <$> getConfig "annex.backends" ""
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parseBackendList [] = list
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parseBackendList s = map lookupBackendName $ words s
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{- Generates a key for a file, trying each backend in turn until one
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- accepts it. -}
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genKey :: FilePath -> Maybe Backend -> Annex (Maybe (Key, Backend))
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genKey file trybackend = do
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bs <- orderedList
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let bs' = maybe bs (: bs) trybackend
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genKey' bs' file
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genKey' :: [Backend] -> FilePath -> Annex (Maybe (Key, Backend))
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genKey' [] _ = return Nothing
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genKey' (b:bs) file = do
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r <- B.getKey b file
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case r of
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Nothing -> genKey' bs file
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Just k -> return $ Just (makesane k, b)
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where
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-- keyNames should not contain newline characters.
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makesane k = k { keyName = map fixbadchar (keyName k) }
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fixbadchar c
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| c == '\n' = '_'
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| otherwise = c
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{- Looks up the key and backend corresponding to an annexed file,
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- by examining what the file symlinks to. -}
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lookupFile :: FilePath -> Annex (Maybe (Key, Backend))
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lookupFile file = do
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tl <- liftIO $ tryIO getsymlink
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case tl of
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Left _ -> return Nothing
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Right l -> makekey l
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where
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getsymlink = takeFileName <$> readSymbolicLink file
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makekey l = maybe (return Nothing) (makeret l) (fileKey l)
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makeret l k = let bname = keyBackendName k in
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case maybeLookupBackendName bname of
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Just backend -> return $ Just (k, backend)
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Nothing -> do
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when (isLinkToAnnex l) $ warning $
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"skipping " ++ file ++
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" (unknown backend " ++
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bname ++ ")"
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return Nothing
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{- Looks up the backend that should be used for a file.
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- That can be configured on a per-file basis in the gitattributes file.
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-}
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chooseBackend :: FilePath -> Annex (Maybe Backend)
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chooseBackend f = Annex.getState Annex.forcebackend >>= go
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where
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go Nothing = maybeLookupBackendName <$>
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checkAttr "annex.backend" f
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go (Just _) = Just . Prelude.head <$> orderedList
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{- Looks up a backend by name. May fail if unknown. -}
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lookupBackendName :: String -> Backend
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lookupBackendName s = fromMaybe unknown $ maybeLookupBackendName s
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where
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unknown = error $ "unknown backend " ++ s
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maybeLookupBackendName :: String -> Maybe Backend
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maybeLookupBackendName s = headMaybe matches
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where
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matches = filter (\b -> s == B.name b) list
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