126 lines
3.1 KiB
Haskell
126 lines
3.1 KiB
Haskell
{- git-annex SHA backend
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-
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- Copyright 2011 Joey Hess <joey@kitenet.net>
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-
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- Licensed under the GNU GPL version 3 or higher.
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-}
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module Backend.SHA (backends) where
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import Control.Monad.State
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import Data.String.Utils
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import System.Cmd.Utils
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import System.IO
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import System.Directory
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import Data.Maybe
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import System.Posix.Files
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import System.FilePath
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import Messages
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import qualified Annex
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import Locations
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import Content
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import Types
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import Types.Backend
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import Types.Key
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import Utility.SafeCommand
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import qualified Build.SysConfig as SysConfig
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type SHASize = Int
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sizes :: [Int]
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sizes = [1, 256, 512, 224, 384]
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backends :: [Backend Annex]
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-- order is slightly significant; want sha1 first, and more general
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-- sizes earlier
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backends = catMaybes $ map genBackend sizes ++ map genBackendE sizes
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genBackend :: SHASize -> Maybe (Backend Annex)
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genBackend size
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| shaCommand size == Nothing = Nothing
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| otherwise = Just b
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where
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b = Types.Backend.Backend
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{ name = shaName size
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, getKey = keyValue size
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, fsckKey = checkKeyChecksum size
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}
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genBackendE :: SHASize -> Maybe (Backend Annex)
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genBackendE size =
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case genBackend size of
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Nothing -> Nothing
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Just b -> Just $ b
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{ name = shaNameE size
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, getKey = keyValueE size
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}
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shaCommand :: SHASize -> Maybe String
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shaCommand 1 = SysConfig.sha1
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shaCommand 256 = SysConfig.sha256
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shaCommand 224 = SysConfig.sha224
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shaCommand 384 = SysConfig.sha384
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shaCommand 512 = SysConfig.sha512
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shaCommand _ = Nothing
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shaName :: SHASize -> String
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shaName size = "SHA" ++ show size
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shaNameE :: SHASize -> String
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shaNameE size = shaName size ++ "E"
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shaN :: SHASize -> FilePath -> Annex String
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shaN size file = do
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showAction "checksum"
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liftIO $ pOpen ReadFromPipe command (toCommand [File file]) $ \h -> do
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line <- hGetLine h
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let bits = split " " line
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if null bits
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then error $ command ++ " parse error"
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else return $ head bits
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where
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command = fromJust $ shaCommand size
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{- A key is a checksum of its contents. -}
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keyValue :: SHASize -> FilePath -> Annex (Maybe Key)
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keyValue size file = do
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s <- shaN size file
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stat <- liftIO $ getFileStatus file
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return $ Just $ stubKey
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{ keyName = s
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, keyBackendName = shaName size
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, keySize = Just $ fromIntegral $ fileSize stat
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}
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{- Extension preserving keys. -}
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keyValueE :: SHASize -> FilePath -> Annex (Maybe Key)
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keyValueE size file = keyValue size file >>= maybe (return Nothing) addE
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where
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addE k = return $ Just $ k
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{ keyName = keyName k ++ extension
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, keyBackendName = shaNameE size
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}
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naiveextension = takeExtension file
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extension =
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if length naiveextension > 6
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then "" -- probably not really an extension
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else naiveextension
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{- A key's checksum is checked during fsck. -}
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checkKeyChecksum :: SHASize -> Key -> Annex Bool
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checkKeyChecksum size key = do
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g <- Annex.gitRepo
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fast <- Annex.getState Annex.fast
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let file = gitAnnexLocation g key
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present <- liftIO $ doesFileExist file
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if not present || fast
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then return True
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else do
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s <- shaN size file
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if s == dropExtension (keyName key)
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then return True
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else do
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dest <- moveBad key
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warning $ "Bad file content; moved to " ++ dest
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return False
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