git-annex/Backend/VURL/Utilities.hs
Joey Hess e7652b0997
implement URL to VURL migration
This needs the content to be present in order to hash it. But it's not
possible for a module used by Backend.URL to call inAnnex because that
would entail a dependency loop. So instead, rely on the fact that
Command.Migrate calls inAnnex before performing a migration.

But, Command.ExamineKey calls fastMigrate and the key may or may not
exist, and it's not wanting to actually perform a migration in any case.
To handle that, had to add an additional value to fastMigrate to
indicate whether the content is inAnnex.

Factored generateEquivilantKey out of Remote.Web.

Note that migrateFromURLToVURL hardcodes use of the SHA256E backend.
It would have been difficult not to, given all the dependency loop
issues. But --backend and annex.backend are used to tell git-annex
migrate to use VURL in any case, so there's no config knob that
the user could expect to configure that.

Sponsored-by: Brock Spratlen on Patreon
2024-03-01 16:42:02 -04:00

51 lines
1.6 KiB
Haskell

{- git-annex VURL backend utilities
-
- Copyright 2024 Joey Hess <id@joeyh.name>
-
- Licensed under the GNU AGPL version 3 or higher.
-}
module Backend.VURL.Utilities where
import Annex.Common
import Types.Key
import Types.Backend
import Types.KeySource
import Logs.EquivilantKeys
import qualified Backend.Hash
import Utility.Metered
migrateFromURLToVURL :: Key -> Backend -> AssociatedFile -> Bool -> Annex (Maybe Key)
migrateFromURLToVURL oldkey newbackend _af inannex
| inannex && fromKey keyVariety oldkey == URLKey && backendVariety newbackend == VURLKey = do
let newkey = mkKey $ const $
(keyData oldkey)
{ keyVariety = VURLKey }
contentfile <- calcRepo (gitAnnexLocation oldkey)
generateEquivilantKey hashbackend contentfile >>= \case
Nothing -> return Nothing
Just ek -> do
setEquivilantKey newkey ek
return (Just newkey)
| otherwise = do
liftIO $ print ("migrateFromURL", inannex, fromKey keyVariety oldkey)
return Nothing
where
-- Relies on the first hash being cryptographically secure, and the
-- default hash used by git-annex.
hashbackend = Prelude.head Backend.Hash.backends
-- The Backend must use a cryptographically secure hash.
generateEquivilantKey :: Backend -> RawFilePath -> Annex (Maybe Key)
generateEquivilantKey b f =
case genKey b of
Just genkey -> do
showSideAction (UnquotedString Backend.Hash.descChecksum)
Just <$> genkey source nullMeterUpdate
Nothing -> return Nothing
where
source = KeySource
{ keyFilename = mempty -- avoid adding any extension
, contentLocation = f
, inodeCache = Nothing
}