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
This commit is contained in:
Joey Hess 2024-03-01 16:42:02 -04:00
parent 2b5ba03c01
commit e7652b0997
No known key found for this signature in database
GPG key ID: DB12DB0FF05F8F38
14 changed files with 82 additions and 34 deletions

View file

@ -53,8 +53,10 @@ cryptographicallySecure (Blake2spHash _) = True
cryptographicallySecure SHA1Hash = False
cryptographicallySecure MD5Hash = False
{- Order is slightly significant; want SHA256 first, and more general
- sizes earlier. -}
{- Order is significant. The first hash is the default one that git-annex
- uses, and must be cryptographically secure.
-
- Also, want more common sizes earlier than uncommon sizes. -}
hashes :: [Hash]
hashes = concat
[ map (SHA2Hash . HashSize) [256, 512, 224, 384]
@ -167,8 +169,8 @@ needsUpgrade key = or
, not (hasExt (fromKey keyVariety key)) && keyHash key /= S.fromShort (fromKey keyName key)
]
trivialMigrate :: Key -> Backend -> AssociatedFile -> Annex (Maybe Key)
trivialMigrate oldkey newbackend afile = trivialMigrate' oldkey newbackend afile
trivialMigrate :: Key -> Backend -> AssociatedFile -> Bool -> Annex (Maybe Key)
trivialMigrate oldkey newbackend afile _inannex = trivialMigrate' oldkey newbackend afile
<$> (annexMaxExtensionLength <$> Annex.getGitConfig)
trivialMigrate' :: Key -> Backend -> AssociatedFile -> Maybe Int -> Maybe Key

View file

@ -14,6 +14,7 @@ import Annex.Common
import Types.Key
import Types.Backend
import Backend.Utilities
import Backend.VURL.Utilities (migrateFromURLToVURL)
backends :: [Backend]
backends = [backendURL]
@ -25,7 +26,7 @@ backendURL = Backend
, verifyKeyContent = Nothing
, verifyKeyContentIncrementally = Nothing
, canUpgradeKey = Nothing
, fastMigrate = Nothing
, fastMigrate = Just migrateFromURLToVURL
-- The content of an url can change at any time, so URL keys are
-- not stable.
, isStableKey = const False

View file

@ -99,4 +99,3 @@ backendVURL = Backend
allowedequiv ek = fromKey keyVariety ek /= VURLKey
varietymap = makeVarietyMap regularBackendList
getbackend ek = maybeLookupBackendVarietyMap (fromKey keyVariety ek) varietymap

51
Backend/VURL/Utilities.hs Normal file
View file

@ -0,0 +1,51 @@
{- 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
}

View file

@ -25,6 +25,10 @@ regularBackendList = Backend.Hash.backends
++ Backend.WORM.backends
++ Backend.URL.backends
{- The default hashing backend. -}
defaultHashBackend :: Backend
defaultHashBackend = Prelude.head regularBackendList
makeVarietyMap :: [Backend] -> M.Map KeyVariety Backend
makeVarietyMap l = M.fromList $ zip (map backendVariety l) l

View file

@ -59,8 +59,8 @@ needsUpgrade :: Key -> Bool
needsUpgrade key =
any (`S8.elem` S.fromShort (fromKey keyName key)) [' ', '\r']
removeProblemChars :: Key -> Backend -> AssociatedFile -> Annex (Maybe Key)
removeProblemChars oldkey newbackend _
removeProblemChars :: Key -> Backend -> AssociatedFile -> Bool -> Annex (Maybe Key)
removeProblemChars oldkey newbackend _ _
| migratable = return $ Just $ alterKey oldkey $ \d -> d
{ keyName = S.toShort $ encodeBS $ reSanitizeKeyName $ decodeBS $ S.fromShort $ keyName d }
| otherwise = return Nothing