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{- git-annex "WORM" backend -- Write Once, Read Many
- -}
module Backend.WORM (backend) where
import Control.Monad.State
import System.FilePath
import System.Posix.Files
import qualified Data.ByteString.Lazy.Char8 as B
import qualified Backend.File
import TypeInternals
import Utility
backend = Backend.File.backend {
name = "WORM",
getKey = keyValue
}
-- The key is formed from the file size, modification time, and the
-- basename of the filename.
--
-- That allows multiple files with the same names to have different keys,
-- while also allowing a file to be moved around while retaining the
-- same key.
keyValue :: FilePath -> Annex (Maybe Key)
keyValue file = do
stat <- liftIO $ getFileStatus file
return $ Just $ Key ((name backend), key stat)
where
key stat = uniqueid stat ++ sep ++ base
uniqueid stat = (show $ modificationTime stat) ++ sep ++
(show $ fileSize stat)
base = takeFileName file
sep = ":"
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