git-annex/Annex/UUID.hs
2012-12-13 00:24:19 -04:00

77 lines
1.9 KiB
Haskell

{- 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
-
- Copyright 2010-2011 Joey Hess <joey@kitenet.net>
-
- Licensed under the GNU GPL version 3 or higher.
-}
module Annex.UUID (
getUUID,
getRepoUUID,
getUncachedUUID,
prepUUID,
genUUID,
removeRepoUUID,
storeUUID,
) where
import Common.Annex
import qualified Git
import qualified Git.Config
import qualified Build.SysConfig as SysConfig
import Config
configkey :: ConfigKey
configkey = annexConfig "uuid"
{- Generates a UUID. There is a library for this, but it's not packaged,
- so use the command line tool. -}
genUUID :: IO UUID
genUUID = gen . lines <$> readProcess command params
where
gen [] = error $ "no output from " ++ command
gen (l:_) = toUUID l
(command:params) = words SysConfig.uuid
{- Get current repository's UUID. -}
getUUID :: Annex UUID
getUUID = getRepoUUID =<< gitRepo
{- Looks up a repo's UUID, caching it in .git/config if it's not already. -}
getRepoUUID :: Git.Repo -> Annex UUID
getRepoUUID r = do
c <- toUUID <$> getConfig cachekey ""
let u = getUncachedUUID r
if c /= u && u /= NoUUID
then do
updatecache u
return u
else return c
where
updatecache u = do
g <- gitRepo
when (g /= r) $ storeUUID cachekey u
cachekey = remoteConfig r "uuid"
removeRepoUUID :: Annex ()
removeRepoUUID = unsetConfig configkey
getUncachedUUID :: Git.Repo -> UUID
getUncachedUUID = toUUID . Git.Config.get key ""
where
(ConfigKey key) = configkey
{- Make sure that the repo has an annex.uuid setting. -}
prepUUID :: Annex ()
prepUUID = whenM ((==) NoUUID <$> getUUID) $
storeUUID configkey =<< liftIO genUUID
storeUUID :: ConfigKey -> UUID -> Annex ()
storeUUID configfield = setConfig configfield . fromUUID