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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 qualified Backend.File
import BackendClass
import Messages
import qualified Annex
import Locations
import Content
import Types
import Utility
import qualified SysConfig
import Key
type SHASize = Int
backends :: [Backend Annex]
-- order is slightly significant; want sha1 first ,and more general
-- sizes earlier
backends = catMaybes $ map genBackend [1, 256, 512, 224, 384]
genBackend :: SHASize -> Maybe (Backend Annex)
genBackend size
| shaCommand size /= "" = Just b
| otherwise = Nothing
where
b = Backend.File.backend
{ name = shaName size
, getKey = keyValue size
, fsckKey = Backend.File.checkKey $ checkKeyChecksum size
}
shaCommand :: SHASize -> String
shaCommand 1 = SysConfig.sha1
shaCommand 256 = SysConfig.sha256
shaCommand 224 = SysConfig.sha224
shaCommand 384 = SysConfig.sha384
shaCommand 512 = SysConfig.sha512
shaCommand _ = ""
shaName :: SHASize -> String
shaName size = "SHA" ++ show size
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 = 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
}
-- 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 == keyName key
then return True
else do
dest <- moveBad key
warning $ "Bad file content; moved to " ++ dest
return False
|
