git-annex/Backend/SHA.hs
Joey Hess 90319afa41 fsck --from
Fscking a remote is now supported. It's done by retrieving
the contents of the specified files from the remote, and checking them,
so can be an expensive operation.

(Several optimisations are possible, to speed it up, of course.. This is
the slow and stupid remote fsck to start with.)

Still, if the remote is a special remote, or a git repository that you
cannot run fsck in locally, it's nice to have the ability to fsck it.

If you have any directory special remotes, now would be a good time to
fsck them, in case you were hit by the data loss bug fixed in the
previous release!
2012-01-19 15:24:05 -04:00

109 lines
2.8 KiB
Haskell

{- git-annex SHA backend
-
- Copyright 2011 Joey Hess <joey@kitenet.net>
-
- Licensed under the GNU GPL version 3 or higher.
-}
module Backend.SHA (backends) where
import Common.Annex
import qualified Annex
import Types.Backend
import Types.Key
import qualified Build.SysConfig as SysConfig
type SHASize = Int
-- order is slightly significant; want SHA256 first, and more general
-- sizes earlier
sizes :: [Int]
sizes = [256, 1, 512, 224, 384]
backends :: [Backend]
backends = catMaybes $ map genBackend sizes ++ map genBackendE sizes
genBackend :: SHASize -> Maybe Backend
genBackend size
| isNothing (shaCommand size) = Nothing
| otherwise = Just b
where
b = Backend
{ name = shaName size
, getKey = keyValue size
, fsckKey = Just $ checkKeyChecksum size
}
genBackendE :: SHASize -> Maybe Backend
genBackendE size =
case genBackend size of
Nothing -> Nothing
Just b -> Just $ b
{ name = shaNameE size
, getKey = keyValueE size
}
shaCommand :: SHASize -> Maybe String
shaCommand 1 = SysConfig.sha1
shaCommand 256 = SysConfig.sha256
shaCommand 224 = SysConfig.sha224
shaCommand 384 = SysConfig.sha384
shaCommand 512 = SysConfig.sha512
shaCommand _ = Nothing
shaName :: SHASize -> String
shaName size = "SHA" ++ show size
shaNameE :: SHASize -> String
shaNameE size = shaName size ++ "E"
shaN :: SHASize -> FilePath -> Annex String
shaN size file = do
showAction "checksum"
liftIO $ pOpen ReadFromPipe command (toCommand [File file]) $ \h -> do
sha <- fst . separate (== ' ') <$> hGetLine h
if null sha
then error $ command ++ " parse error"
else return sha
where
command = fromJust $ shaCommand size
{- A key is a checksum of its contents. -}
keyValue :: SHASize -> FilePath -> Annex (Maybe Key)
keyValue size file = do
s <- shaN size file
stat <- liftIO $ getFileStatus file
return $ Just $ stubKey
{ keyName = s
, keyBackendName = shaName size
, keySize = Just $ fromIntegral $ fileSize stat
}
{- Extension preserving keys. -}
keyValueE :: SHASize -> FilePath -> Annex (Maybe Key)
keyValueE size file = keyValue size file >>= maybe (return Nothing) addE
where
addE k = return $ Just $ k
{ keyName = keyName k ++ extension
, keyBackendName = shaNameE size
}
naiveextension = takeExtension file
extension
-- long or newline containing extensions are
-- probably not really an extension
| length naiveextension > 6 ||
'\n' `elem` naiveextension = ""
| otherwise = naiveextension
{- A key's checksum is checked during fsck. -}
checkKeyChecksum :: SHASize -> Key -> FilePath -> Annex Bool
checkKeyChecksum size key file = do
fast <- Annex.getState Annex.fast
present <- liftIO $ doesFileExist file
if not present || fast
then return True
else check <$> shaN size file
where
check s
| s == dropExtension (keyName key) = True
| otherwise = False