314 lines
11 KiB
Haskell
314 lines
11 KiB
Haskell
{- git-annex hashing backends
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-
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- Copyright 2011-2024 Joey Hess <id@joeyh.name>
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-
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- Licensed under the GNU AGPL version 3 or higher.
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-}
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{-# LANGUAGE OverloadedStrings #-}
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module Backend.Hash (
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backends,
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testKeyBackend,
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keyHash,
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descChecksum,
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Hash(..),
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cryptographicallySecure,
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hashFile,
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checkKeyChecksum
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) where
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import Annex.Common
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import qualified Annex
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import Backend.Utilities
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import Types.Key
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import Types.Backend
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import Types.KeySource
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import Utility.Hash
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import Utility.Metered
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import qualified Utility.RawFilePath as R
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import qualified Data.ByteString as S
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import qualified Data.ByteString.Short as S (toShort, fromShort)
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import qualified Data.ByteString.Char8 as S8
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import qualified Data.ByteString.Lazy as L
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import Control.DeepSeq
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import Control.Exception (evaluate)
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data Hash
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= MD5Hash
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| SHA1Hash
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| SHA2Hash HashSize
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| SHA3Hash HashSize
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| SkeinHash HashSize
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| Blake2bHash HashSize
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| Blake2bpHash HashSize
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| Blake2sHash HashSize
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| Blake2spHash HashSize
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cryptographicallySecure :: Hash -> Bool
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cryptographicallySecure (SHA2Hash _) = True
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cryptographicallySecure (SHA3Hash _) = True
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cryptographicallySecure (SkeinHash _) = True
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cryptographicallySecure (Blake2bHash _) = True
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cryptographicallySecure (Blake2bpHash _) = True
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cryptographicallySecure (Blake2sHash _) = True
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cryptographicallySecure (Blake2spHash _) = True
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cryptographicallySecure SHA1Hash = False
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cryptographicallySecure MD5Hash = False
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{- Order is significant. The first hash is the default one that git-annex
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- uses, and must be cryptographically secure.
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-
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- Also, want more common sizes earlier than uncommon sizes. -}
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hashes :: [Hash]
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hashes = concat
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[ map (SHA2Hash . HashSize) [256, 512, 224, 384]
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, map (SHA3Hash . HashSize) [256, 512, 224, 384]
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, map (SkeinHash . HashSize) [256, 512]
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, map (Blake2bHash . HashSize) [256, 512, 160, 224, 384]
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, map (Blake2bpHash . HashSize) [512]
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, map (Blake2sHash . HashSize) [256, 160, 224]
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, map (Blake2spHash . HashSize) [256, 224]
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, [SHA1Hash]
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, [MD5Hash]
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]
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{- The SHA256E backend is the default, so genBackendE comes first. -}
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backends :: [Backend]
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backends = concatMap (\h -> [genBackendE h, genBackend h]) hashes
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genBackend :: Hash -> Backend
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genBackend hash = Backend
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{ backendVariety = hashKeyVariety hash (HasExt False)
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, genKey = Just (keyValue hash)
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, verifyKeyContent = Just $ checkKeyChecksum sameCheckSum hash
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, verifyKeyContentIncrementally = Just $ checkKeyChecksumIncremental hash
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, canUpgradeKey = Just needsUpgrade
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, fastMigrate = Just trivialMigrate
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, isStableKey = const True
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, isCryptographicallySecure = cryptographicallySecure hash
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, isCryptographicallySecureKey = const $ pure $
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cryptographicallySecure hash
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}
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genBackendE :: Hash -> Backend
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genBackendE hash = (genBackend hash)
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{ backendVariety = hashKeyVariety hash (HasExt True)
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, genKey = Just (keyValueE hash)
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}
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hashKeyVariety :: Hash -> HasExt -> KeyVariety
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hashKeyVariety MD5Hash he = MD5Key he
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hashKeyVariety SHA1Hash he = SHA1Key he
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hashKeyVariety (SHA2Hash size) he = SHA2Key size he
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hashKeyVariety (SHA3Hash size) he = SHA3Key size he
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hashKeyVariety (SkeinHash size) he = SKEINKey size he
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hashKeyVariety (Blake2bHash size) he = Blake2bKey size he
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hashKeyVariety (Blake2bpHash size) he = Blake2bpKey size he
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hashKeyVariety (Blake2sHash size) he = Blake2sKey size he
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hashKeyVariety (Blake2spHash size) he = Blake2spKey size he
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{- A key is a hash of its contents. -}
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keyValue :: Hash -> KeySource -> MeterUpdate -> Annex Key
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keyValue hash source meterupdate = do
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let file = contentLocation source
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filesize <- liftIO $ getFileSize file
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s <- hashFile hash file meterupdate
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return $ mkKey $ \k -> k
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{ keyName = S.toShort (encodeBS s)
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, keyVariety = hashKeyVariety hash (HasExt False)
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, keySize = Just filesize
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}
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{- Extension preserving keys. -}
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keyValueE :: Hash -> KeySource -> MeterUpdate -> Annex Key
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keyValueE hash source meterupdate =
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keyValue hash source meterupdate
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>>= addE source (const $ hashKeyVariety hash (HasExt True))
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checkKeyChecksum :: (Key -> String -> Bool) -> Hash -> Key -> RawFilePath -> Annex Bool
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checkKeyChecksum issame hash key file = catchIOErrorType HardwareFault hwfault $ do
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fast <- Annex.getRead Annex.fast
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exists <- liftIO $ R.doesPathExist file
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case (exists, fast) of
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(True, False) -> do
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showAction (UnquotedString descChecksum)
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issame key
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<$> hashFile hash file nullMeterUpdate
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_ -> return True
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where
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hwfault e = do
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warning $ UnquotedString $ "hardware fault: " ++ show e
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return False
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sameCheckSum :: Key -> String -> Bool
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sameCheckSum key s
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| s == expected = True
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{- A bug caused checksums to be prefixed with \ in some
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- cases; still accept these as legal now that the bug
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- has been fixed. -}
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| '\\' : s == expected = True
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| otherwise = False
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where
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expected = decodeBS (keyHash key)
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checkKeyChecksumIncremental :: Hash -> Key -> Annex IncrementalVerifier
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checkKeyChecksumIncremental hash key = liftIO $ (snd $ hasher hash) key
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keyHash :: Key -> S.ByteString
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keyHash = fst . splitKeyNameExtension
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{- Upgrade keys that have the \ prefix on their hash due to a bug, or
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- that contain non-alphanumeric characters in their extension.
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-
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- Also, for a while migrate from eg SHA256E to SHA256 resulted in a SHA256
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- key that contained an extension inside its keyName. Upgrade those
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- keys, removing the extension.
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-}
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needsUpgrade :: Key -> Bool
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needsUpgrade key = or
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[ "\\" `S8.isPrefixOf` keyHash key
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, S.any (not . validInExtension) (snd $ splitKeyNameExtension key)
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, not (hasExt (fromKey keyVariety key)) && keyHash key /= S.fromShort (fromKey keyName key)
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]
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trivialMigrate :: Key -> Backend -> AssociatedFile -> Bool -> Annex (Maybe Key)
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trivialMigrate oldkey newbackend afile _inannex = do
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c <- Annex.getGitConfig
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return $ trivialMigrate' oldkey newbackend afile
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(annexMaxExtensionLength c)
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(annexMaxExtensions c)
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trivialMigrate' :: Key -> Backend -> AssociatedFile -> Maybe Int -> Maybe Int -> Maybe Key
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trivialMigrate' oldkey newbackend afile maxextlen maxexts
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{- Fast migration from hashE to hash backend. -}
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| migratable && hasExt oldvariety = Just $ alterKey oldkey $ \d -> d
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{ keyName = S.toShort (keyHash oldkey)
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, keyVariety = newvariety
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}
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{- Fast migration from hash to hashE backend. -}
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| migratable && hasExt newvariety = case afile of
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AssociatedFile Nothing -> Nothing
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AssociatedFile (Just file) -> Just $ alterKey oldkey $ \d -> d
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{ keyName = S.toShort $ keyHash oldkey
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<> selectExtension maxextlen maxexts file
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, keyVariety = newvariety
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}
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{- Upgrade to fix bad previous migration that created a
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- non-extension preserving key, with an extension
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- in its keyName. -}
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| newvariety == oldvariety && not (hasExt oldvariety) &&
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keyHash oldkey /= S.fromShort (fromKey keyName oldkey) =
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Just $ alterKey oldkey $ \d -> d
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{ keyName = S.toShort (keyHash oldkey)
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}
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| otherwise = Nothing
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where
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migratable = oldvariety /= newvariety
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&& sameExceptExt oldvariety newvariety
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oldvariety = fromKey keyVariety oldkey
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newvariety = backendVariety newbackend
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hashFile :: Hash -> RawFilePath -> MeterUpdate -> Annex String
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hashFile hash file meterupdate =
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liftIO $ withMeteredFile (fromRawFilePath file) meterupdate $ \b -> do
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let h = (fst $ hasher hash) b
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-- Force full evaluation of hash so whole file is read
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-- before returning.
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evaluate (rnf h)
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return h
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type Hasher = (L.ByteString -> String, Key -> IO IncrementalVerifier)
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hasher :: Hash -> Hasher
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hasher MD5Hash = md5Hasher
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hasher SHA1Hash = sha1Hasher
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hasher (SHA2Hash hashsize) = sha2Hasher hashsize
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hasher (SHA3Hash hashsize) = sha3Hasher hashsize
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hasher (SkeinHash hashsize) = skeinHasher hashsize
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hasher (Blake2bHash hashsize) = blake2bHasher hashsize
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hasher (Blake2bpHash hashsize) = blake2bpHasher hashsize
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hasher (Blake2sHash hashsize) = blake2sHasher hashsize
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hasher (Blake2spHash hashsize) = blake2spHasher hashsize
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mkHasher :: HashAlgorithm h => (L.ByteString -> Digest h) -> Context h -> Hasher
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mkHasher h c = (show . h, mkIncrementalVerifier c descChecksum . sameCheckSum)
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sha2Hasher :: HashSize -> Hasher
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sha2Hasher (HashSize hashsize)
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| hashsize == 256 = mkHasher sha2_256 sha2_256_context
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| hashsize == 224 = mkHasher sha2_224 sha2_224_context
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| hashsize == 384 = mkHasher sha2_384 sha2_384_context
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| hashsize == 512 = mkHasher sha2_512 sha2_512_context
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| otherwise = giveup $ "unsupported SHA2 size " ++ show hashsize
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sha3Hasher :: HashSize -> Hasher
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sha3Hasher (HashSize hashsize)
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| hashsize == 256 = mkHasher sha3_256 sha3_256_context
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| hashsize == 224 = mkHasher sha3_224 sha3_224_context
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| hashsize == 384 = mkHasher sha3_384 sha3_384_context
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| hashsize == 512 = mkHasher sha3_512 sha3_512_context
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| otherwise = giveup $ "unsupported SHA3 size " ++ show hashsize
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skeinHasher :: HashSize -> Hasher
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skeinHasher (HashSize hashsize)
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| hashsize == 256 = mkHasher skein256 skein256_context
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| hashsize == 512 = mkHasher skein512 skein512_context
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| otherwise = giveup $ "unsupported SKEIN size " ++ show hashsize
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blake2bHasher :: HashSize -> Hasher
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blake2bHasher (HashSize hashsize)
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| hashsize == 256 = mkHasher blake2b_256 blake2b_256_context
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| hashsize == 512 = mkHasher blake2b_512 blake2b_512_context
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| hashsize == 160 = mkHasher blake2b_160 blake2b_160_context
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| hashsize == 224 = mkHasher blake2b_224 blake2b_224_context
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| hashsize == 384 = mkHasher blake2b_384 blake2b_384_context
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| otherwise = giveup $ "unsupported BLAKE2B size " ++ show hashsize
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blake2bpHasher :: HashSize -> Hasher
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blake2bpHasher (HashSize hashsize)
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| hashsize == 512 = mkHasher blake2bp_512 blake2bp_512_context
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| otherwise = giveup $ "unsupported BLAKE2BP size " ++ show hashsize
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blake2sHasher :: HashSize -> Hasher
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blake2sHasher (HashSize hashsize)
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| hashsize == 256 = mkHasher blake2s_256 blake2s_256_context
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| hashsize == 160 = mkHasher blake2s_160 blake2s_160_context
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| hashsize == 224 = mkHasher blake2s_224 blake2s_224_context
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| otherwise = giveup $ "unsupported BLAKE2S size " ++ show hashsize
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blake2spHasher :: HashSize -> Hasher
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blake2spHasher (HashSize hashsize)
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| hashsize == 256 = mkHasher blake2sp_256 blake2sp_256_context
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| hashsize == 224 = mkHasher blake2sp_224 blake2sp_224_context
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| otherwise = giveup $ "unsupported BLAKE2SP size " ++ show hashsize
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sha1Hasher :: Hasher
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sha1Hasher = mkHasher sha1 sha1_context
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md5Hasher :: Hasher
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md5Hasher = mkHasher md5 md5_context
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descChecksum :: String
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descChecksum = "checksum"
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{- A variant of the SHA256E backend, for testing that needs special keys
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- that cannot collide with legitimate keys in the repository.
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-
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- This is accomplished by appending a special extension to the key,
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- that is not one that selectExtension would select (due to being too
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- long).
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-}
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testKeyBackend :: Backend
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testKeyBackend =
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let b = genBackendE (SHA2Hash (HashSize 256))
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gk = case genKey b of
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Nothing -> Nothing
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Just f -> Just (\ks p -> addTestE <$> f ks p)
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in b { genKey = gk }
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where
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addTestE k = alterKey k $ \d -> d
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{ keyName = keyName d <> longext
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}
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longext = ".this-is-a-test-key"
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