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|
{- git-annex SHA abstract backend
-
- Copyright 2011 Joey Hess <joey@kitenet.net>
-
- Licensed under the GNU GPL version 3 or higher.
-}
module Backend.SHA (backends) where
import Control.Monad.State
import Data.String.Utils
import System.Cmd.Utils
import System.IO
import System.Directory
import Data.Maybe
import System.Posix.Files
import System.FilePath
import qualified Backend.File
import Messages
import qualified Annex
import Locations
import Content
import Types
import Types.Backend
import Types.Key
import Utility
import qualified SysConfig
type SHASize = Int
sizes :: [Int]
sizes = [1, 256, 512, 224, 384]
backends :: [Backend Annex]
-- order is slightly significant; want sha1 first ,and more general
-- sizes earlier
backends = catMaybes $ map genBackend sizes ++ map genBackendE sizes
genBackend :: SHASize -> Maybe (Backend Annex)
genBackend size
| shaCommand size == Nothing = Nothing
| otherwise = Just b
where
b = Backend.File.backend
{ name = shaName size
, getKey = keyValue size
, fsckKey = Backend.File.checkKey $ checkKeyChecksum size
}
genBackendE :: SHASize -> Maybe (Backend Annex)
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
showNote "checksum..."
liftIO $ pOpen ReadFromPipe command (toCommand [File file]) $ \h -> do
line <- hGetLine h
let bits = split " " line
if null bits
then error $ command ++ " parse error"
else return $ head bits
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 =
if length naiveextension > 6
then "" -- probably not really an extension
else naiveextension
-- A key's checksum is checked during fsck.
checkKeyChecksum :: SHASize -> Key -> Annex Bool
checkKeyChecksum size key = do
g <- Annex.gitRepo
fast <- Annex.getState Annex.fast
let file = gitAnnexLocation g key
present <- liftIO $ doesFileExist file
if (not present || fast)
then return True
else do
s <- shaN size file
if s == dropExtension (keyName key)
then return True
else do
dest <- moveBad key
warning $ "Bad file content; moved to " ++ dest
return False
|
