git-annex/UUID.hs

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{- git-annex uuids
-
- Each git repository used by git-annex has an annex.uuid setting that
- uniquely identifies that repository.
-
- UUIDs of remotes are cached in git config, using keys named
- remote.<name>.annex-uuid
-
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- Copyright 2010 Joey Hess <joey@kitenet.net>
-
- Licensed under the GNU GPL version 3 or higher.
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-}
module UUID (
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UUID,
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getUUID,
getUncachedUUID,
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prepUUID,
genUUID,
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describeUUID,
uuidMap,
uuidLog
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) where
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import Control.Monad.State
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import System.Cmd.Utils
import System.IO
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import qualified Data.Map as M
import Data.Maybe
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import qualified Git
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import qualified Branch
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import Types
import Types.UUID
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import qualified Annex
import qualified SysConfig
import Config
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configkey :: String
configkey = "annex.uuid"
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{- Filename of uuid.log. -}
uuidLog :: FilePath
uuidLog = "uuid.log"
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{- Generates a UUID. There is a library for this, but it's not packaged,
- so use the command line tool. -}
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genUUID :: IO UUID
genUUID = liftIO $ pOpen ReadFromPipe command params $ \h -> hGetLine h
where
command = SysConfig.uuid
params = if command == "uuid"
-- request a random uuid be generated
then ["-m"]
-- uuidgen generates random uuid by default
else []
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{- Looks up a repo's UUID. May return "" if none is known.
-}
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getUUID :: Git.Repo -> Annex UUID
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getUUID r = do
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g <- Annex.gitRepo
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let c = cached g
let u = getUncachedUUID r
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if c /= u && u /= ""
then do
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updatecache g u
return u
else return c
where
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cached g = Git.configGet g cachekey ""
updatecache g u = when (g /= r) $ setConfig cachekey u
cachekey = "remote." ++ fromMaybe "" (Git.repoRemoteName r) ++ ".annex-uuid"
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getUncachedUUID :: Git.Repo -> UUID
getUncachedUUID r = Git.configGet r configkey ""
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{- Make sure that the repo has an annex.uuid setting. -}
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prepUUID :: Annex ()
prepUUID = do
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u <- getUUID =<< Annex.gitRepo
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when ("" == u) $ do
uuid <- liftIO genUUID
setConfig configkey uuid
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{- Records a description for a uuid in the uuidLog. -}
describeUUID :: UUID -> String -> Annex ()
describeUUID uuid desc = do
m <- uuidMap
let m' = M.insert uuid desc m
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Branch.change uuidLog (serialize m')
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where
serialize m = unlines $ map (\(u, d) -> u++" "++d) $ M.toList m
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{- Read and parse the uuidLog into a Map -}
uuidMap :: Annex (M.Map UUID String)
uuidMap = do
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s <- Branch.get uuidLog
return $ M.fromList $ map pair $ lines s
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where
pair l =
if 1 < length (words l)
then (head $ words l, unwords $ drop 1 $ words l)
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else ("", "")