git-annex/Backend/WORM.hs
Joey Hess 13bbb61a51 add key stability checking interface
Needed for resuming from chunks.

Url keys are considered not stable. I considered treating url keys with a
known size as stable, but just don't feel that is enough information.
2014-07-27 12:33:46 -04:00

45 lines
1.1 KiB
Haskell

{- git-annex "WORM" backend -- Write Once, Read Many
-
- Copyright 2010 Joey Hess <joey@kitenet.net>
-
- Licensed under the GNU GPL version 3 or higher.
-}
module Backend.WORM (backends) where
import Common.Annex
import Types.Backend
import Types.Key
import Types.KeySource
import Backend.Utilities
backends :: [Backend]
backends = [backend]
backend :: Backend
backend = Backend
{ name = "WORM"
, getKey = keyValue
, fsckKey = Nothing
, canUpgradeKey = Nothing
, fastMigrate = Nothing
, isStableKey = const True
}
{- The key includes 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 :: KeySource -> Annex (Maybe Key)
keyValue source = do
stat <- liftIO $ getFileStatus $ contentLocation source
n <- genKeyName $ keyFilename source
return $ Just $ stubKey
{ keyName = n
, keyBackendName = name backend
, keySize = Just $ fromIntegral $ fileSize stat
, keyMtime = Just $ modificationTime stat
}