git-annex/Annex/UUID.hs
Joey Hess e5225f08fc
When built with ut uid-1.3.12, generate more random UUIDs than before
Use nextRandom to generate the random UUID, rather than using randomIO.
This gets fixes for the following two bugs in the uuid library.

However, this did not impact git-annex much, so a hard depedency has
not been added on uuid-1.3.12.

https://github.com/aslatter/uuid/issues/15
	"v4 UUIDs are not that random"

	This doesn't greatly affect git-annex, because even with only
	2^64 possible UUIDs, the chance that two git-annex repositories
	that are clones of the same git repo get the same UUID is miniscule.

	And, git-annex generates only one UUID per run, so preducting
	subsequent UUIDs is not a problem.

https://github.com/aslatter/uuid/issues/16
	"Remove Random instance for UUID, or mark it as deprecated"

	git-annex was using that instance; let's stop before it gets
	deprecated or removed.
2016-07-27 07:46:08 -04:00

124 lines
3.2 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 2010-2016 Joey Hess <id@joeyh.name>
-
- Licensed under the GNU GPL version 3 or higher.
-}
module Annex.UUID (
getUUID,
getRepoUUID,
getUncachedUUID,
isUUIDConfigured,
prepUUID,
genUUID,
genUUIDInNameSpace,
gCryptNameSpace,
removeRepoUUID,
storeUUID,
storeUUIDIn,
setUUID,
webUUID,
bitTorrentUUID,
) where
import Annex.Common
import qualified Annex
import qualified Git
import qualified Git.Config
import Config
import qualified Data.UUID as U
import qualified Data.UUID.V4 as U4
import qualified Data.UUID.V5 as U5
import Data.Bits.Utils
configkey :: ConfigKey
configkey = annexConfig "uuid"
{- Generates a random UUID, that does not include the MAC address. -}
genUUID :: IO UUID
genUUID = UUID . show <$> U4.nextRandom
{- Generates a UUID from a given string, using a namespace.
- Given the same namespace, the same string will always result
- in the same UUID. -}
genUUIDInNameSpace :: U.UUID -> String -> UUID
genUUIDInNameSpace namespace = UUID . show . U5.generateNamed namespace . s2w8
{- Namespace used for UUIDs derived from git-remote-gcrypt ids. -}
gCryptNameSpace :: U.UUID
gCryptNameSpace = U5.generateNamed U5.namespaceURL $
s2w8 "http://git-annex.branchable.com/design/gcrypt/"
{- Get current repository's UUID. -}
getUUID :: Annex UUID
getUUID = annexUUID <$> Annex.getGitConfig
{- Looks up a remote repo's UUID, caching it in .git/config if
- it's not already. -}
getRepoUUID :: Git.Repo -> Annex UUID
getRepoUUID r = do
c <- toUUID <$> 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) $ storeUUIDIn cachekey u
cachekey = remoteConfig r "uuid"
removeRepoUUID :: Annex ()
removeRepoUUID = do
unsetConfig configkey
storeUUID NoUUID
getUncachedUUID :: Git.Repo -> UUID
getUncachedUUID = toUUID . Git.Config.get key ""
where
(ConfigKey key) = configkey
-- Does the repo's config have a key for the UUID?
-- True even when the key has no value.
isUUIDConfigured :: Git.Repo -> Bool
isUUIDConfigured = isJust . Git.Config.getMaybe key
where
(ConfigKey key) = configkey
{- Make sure that the repo has an annex.uuid setting. -}
prepUUID :: Annex ()
prepUUID = whenM ((==) NoUUID <$> getUUID) $
storeUUID =<< liftIO genUUID
storeUUID :: UUID -> Annex ()
storeUUID u = do
Annex.changeGitConfig $ \c -> c { annexUUID = u }
storeUUIDIn configkey u
storeUUIDIn :: ConfigKey -> UUID -> Annex ()
storeUUIDIn configfield = setConfig configfield . fromUUID
{- Only sets the configkey in the Repo; does not change .git/config -}
setUUID :: Git.Repo -> UUID -> IO Git.Repo
setUUID r u = do
let s = show configkey ++ "=" ++ fromUUID u
Git.Config.store s r
-- Dummy uuid for the whole web. Do not alter.
webUUID :: UUID
webUUID = UUID "00000000-0000-0000-0000-000000000001"
-- Dummy uuid for bittorrent. Do not alter.
bitTorrentUUID :: UUID
bitTorrentUUID = UUID "00000000-0000-0000-0000-000000000002"