git-annex/Backend/Hash.hs
Joey Hess 19e78816f0
convert Key to ShortByteString
This adds the overhead of a copy when serializing and deserializing keys.
I have not benchmarked much, but runtimes seem barely changed at all by that.

When a lot of keys are in memory, it improves memory use.

And, it prevents keys sometimes getting PINNED in memory and failing to GC,
which is a problem ByteString has sometimes. In particular, git-annex sync
from a borg special remote had that problem and this improved its memory
use by a large amount.

Sponsored-by: Shae Erisson on Patreon
2021-10-05 20:20:08 -04:00

302 lines
10 KiB
Haskell

{- git-annex hashing backends
-
- Copyright 2011-2021 Joey Hess <id@joeyh.name>
-
- Licensed under the GNU AGPL version 3 or higher.
-}
{-# LANGUAGE OverloadedStrings #-}
module Backend.Hash (
backends,
testKeyBackend,
keyHash,
) where
import Annex.Common
import qualified Annex
import Backend.Utilities
import Types.Key
import Types.Backend
import Types.KeySource
import Utility.Hash
import Utility.Metered
import qualified Utility.RawFilePath as R
import qualified Data.ByteString as S
import qualified Data.ByteString.Short as S (toShort, fromShort)
import qualified Data.ByteString.Char8 as S8
import qualified Data.ByteString.Lazy as L
import Control.DeepSeq
import Control.Exception (evaluate)
data Hash
= MD5Hash
| SHA1Hash
| SHA2Hash HashSize
| SHA3Hash HashSize
| SkeinHash HashSize
| Blake2bHash HashSize
| Blake2bpHash HashSize
| Blake2sHash HashSize
| Blake2spHash HashSize
cryptographicallySecure :: Hash -> Bool
cryptographicallySecure (SHA2Hash _) = True
cryptographicallySecure (SHA3Hash _) = True
cryptographicallySecure (SkeinHash _) = True
cryptographicallySecure (Blake2bHash _) = True
cryptographicallySecure (Blake2bpHash _) = True
cryptographicallySecure (Blake2sHash _) = True
cryptographicallySecure (Blake2spHash _) = True
cryptographicallySecure SHA1Hash = False
cryptographicallySecure MD5Hash = False
{- Order is slightly significant; want SHA256 first, and more general
- sizes earlier. -}
hashes :: [Hash]
hashes = concat
[ map (SHA2Hash . HashSize) [256, 512, 224, 384]
, map (SHA3Hash . HashSize) [256, 512, 224, 384]
, map (SkeinHash . HashSize) [256, 512]
, map (Blake2bHash . HashSize) [256, 512, 160, 224, 384]
, map (Blake2bpHash . HashSize) [512]
, map (Blake2sHash . HashSize) [256, 160, 224]
, map (Blake2spHash . HashSize) [256, 224]
, [SHA1Hash]
, [MD5Hash]
]
{- The SHA256E backend is the default, so genBackendE comes first. -}
backends :: [Backend]
backends = concatMap (\h -> [genBackendE h, genBackend h]) hashes
genBackend :: Hash -> Backend
genBackend hash = Backend
{ backendVariety = hashKeyVariety hash (HasExt False)
, genKey = Just (keyValue hash)
, verifyKeyContent = Just $ checkKeyChecksum hash
, verifyKeyContentIncrementally = Just $ checkKeyChecksumIncremental hash
, canUpgradeKey = Just needsUpgrade
, fastMigrate = Just trivialMigrate
, isStableKey = const True
, isCryptographicallySecure = const (cryptographicallySecure hash)
}
genBackendE :: Hash -> Backend
genBackendE hash = (genBackend hash)
{ backendVariety = hashKeyVariety hash (HasExt True)
, genKey = Just (keyValueE hash)
}
hashKeyVariety :: Hash -> HasExt -> KeyVariety
hashKeyVariety MD5Hash he = MD5Key he
hashKeyVariety SHA1Hash he = SHA1Key he
hashKeyVariety (SHA2Hash size) he = SHA2Key size he
hashKeyVariety (SHA3Hash size) he = SHA3Key size he
hashKeyVariety (SkeinHash size) he = SKEINKey size he
hashKeyVariety (Blake2bHash size) he = Blake2bKey size he
hashKeyVariety (Blake2bpHash size) he = Blake2bpKey size he
hashKeyVariety (Blake2sHash size) he = Blake2sKey size he
hashKeyVariety (Blake2spHash size) he = Blake2spKey size he
{- A key is a hash of its contents. -}
keyValue :: Hash -> KeySource -> MeterUpdate -> Annex Key
keyValue hash source meterupdate = do
let file = contentLocation source
filesize <- liftIO $ getFileSize file
s <- hashFile hash file meterupdate
return $ mkKey $ \k -> k
{ keyName = S.toShort (encodeBS s)
, keyVariety = hashKeyVariety hash (HasExt False)
, keySize = Just filesize
}
{- Extension preserving keys. -}
keyValueE :: Hash -> KeySource -> MeterUpdate -> Annex Key
keyValueE hash source meterupdate =
keyValue hash source meterupdate
>>= addE source (const $ hashKeyVariety hash (HasExt True))
checkKeyChecksum :: Hash -> Key -> RawFilePath -> Annex Bool
checkKeyChecksum hash key file = catchIOErrorType HardwareFault hwfault $ do
fast <- Annex.getState Annex.fast
exists <- liftIO $ R.doesPathExist file
case (exists, fast) of
(True, False) -> do
showAction descChecksum
sameCheckSum key
<$> hashFile hash file nullMeterUpdate
_ -> return True
where
hwfault e = do
warning $ "hardware fault: " ++ show e
return False
sameCheckSum :: Key -> String -> Bool
sameCheckSum key s
| s == expected = True
{- A bug caused checksums to be prefixed with \ in some
- cases; still accept these as legal now that the bug
- has been fixed. -}
| '\\' : s == expected = True
| otherwise = False
where
expected = decodeBS (keyHash key)
checkKeyChecksumIncremental :: Hash -> Key -> Annex IncrementalVerifier
checkKeyChecksumIncremental hash key = liftIO $ (snd $ hasher hash) key
keyHash :: Key -> S.ByteString
keyHash = fst . splitKeyNameExtension
{- Upgrade keys that have the \ prefix on their hash due to a bug, or
- that contain non-alphanumeric characters in their extension.
-
- Also, for a while migrate from eg SHA256E to SHA256 resulted in a SHA256
- key that contained an extension inside its keyName. Upgrade those
- keys, removing the extension.
-}
needsUpgrade :: Key -> Bool
needsUpgrade key = or
[ "\\" `S8.isPrefixOf` keyHash key
, S.any (not . validInExtension) (snd $ splitKeyNameExtension key)
, 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
<$> (annexMaxExtensionLength <$> Annex.getGitConfig)
trivialMigrate' :: Key -> Backend -> AssociatedFile -> Maybe Int -> Maybe Key
trivialMigrate' oldkey newbackend afile maxextlen
{- Fast migration from hashE to hash backend. -}
| migratable && hasExt oldvariety = Just $ alterKey oldkey $ \d -> d
{ keyName = S.toShort (keyHash oldkey)
, keyVariety = newvariety
}
{- Fast migration from hash to hashE backend. -}
| migratable && hasExt newvariety = case afile of
AssociatedFile Nothing -> Nothing
AssociatedFile (Just file) -> Just $ alterKey oldkey $ \d -> d
{ keyName = S.toShort $ keyHash oldkey
<> selectExtension maxextlen file
, keyVariety = newvariety
}
{- Upgrade to fix bad previous migration that created a
- non-extension preserving key, with an extension
- in its keyName. -}
| newvariety == oldvariety && not (hasExt oldvariety) &&
keyHash oldkey /= S.fromShort (fromKey keyName oldkey) =
Just $ alterKey oldkey $ \d -> d
{ keyName = S.toShort (keyHash oldkey)
}
| otherwise = Nothing
where
migratable = oldvariety /= newvariety
&& sameExceptExt oldvariety newvariety
oldvariety = fromKey keyVariety oldkey
newvariety = backendVariety newbackend
hashFile :: Hash -> RawFilePath -> MeterUpdate -> Annex String
hashFile hash file meterupdate =
liftIO $ withMeteredFile (fromRawFilePath file) meterupdate $ \b -> do
let h = (fst $ hasher hash) b
-- Force full evaluation of hash so whole file is read
-- before returning.
evaluate (rnf h)
return h
type Hasher = (L.ByteString -> String, Key -> IO IncrementalVerifier)
hasher :: Hash -> Hasher
hasher MD5Hash = md5Hasher
hasher SHA1Hash = sha1Hasher
hasher (SHA2Hash hashsize) = sha2Hasher hashsize
hasher (SHA3Hash hashsize) = sha3Hasher hashsize
hasher (SkeinHash hashsize) = skeinHasher hashsize
hasher (Blake2bHash hashsize) = blake2bHasher hashsize
hasher (Blake2bpHash hashsize) = blake2bpHasher hashsize
hasher (Blake2sHash hashsize) = blake2sHasher hashsize
hasher (Blake2spHash hashsize) = blake2spHasher hashsize
mkHasher :: HashAlgorithm h => (L.ByteString -> Digest h) -> Context h -> Hasher
mkHasher h c = (show . h, mkIncrementalVerifier c descChecksum . sameCheckSum)
sha2Hasher :: HashSize -> Hasher
sha2Hasher (HashSize hashsize)
| hashsize == 256 = mkHasher sha2_256 sha2_256_context
| hashsize == 224 = mkHasher sha2_224 sha2_224_context
| hashsize == 384 = mkHasher sha2_384 sha2_384_context
| hashsize == 512 = mkHasher sha2_512 sha2_512_context
| otherwise = error $ "unsupported SHA2 size " ++ show hashsize
sha3Hasher :: HashSize -> Hasher
sha3Hasher (HashSize hashsize)
| hashsize == 256 = mkHasher sha3_256 sha3_256_context
| hashsize == 224 = mkHasher sha3_224 sha3_224_context
| hashsize == 384 = mkHasher sha3_384 sha3_384_context
| hashsize == 512 = mkHasher sha3_512 sha3_512_context
| otherwise = error $ "unsupported SHA3 size " ++ show hashsize
skeinHasher :: HashSize -> Hasher
skeinHasher (HashSize hashsize)
| hashsize == 256 = mkHasher skein256 skein256_context
| hashsize == 512 = mkHasher skein512 skein512_context
| otherwise = error $ "unsupported SKEIN size " ++ show hashsize
blake2bHasher :: HashSize -> Hasher
blake2bHasher (HashSize hashsize)
| hashsize == 256 = mkHasher blake2b_256 blake2b_256_context
| hashsize == 512 = mkHasher blake2b_512 blake2b_512_context
| hashsize == 160 = mkHasher blake2b_160 blake2b_160_context
| hashsize == 224 = mkHasher blake2b_224 blake2b_224_context
| hashsize == 384 = mkHasher blake2b_384 blake2b_384_context
| otherwise = error $ "unsupported BLAKE2B size " ++ show hashsize
blake2bpHasher :: HashSize -> Hasher
blake2bpHasher (HashSize hashsize)
| hashsize == 512 = mkHasher blake2bp_512 blake2bp_512_context
| otherwise = error $ "unsupported BLAKE2BP size " ++ show hashsize
blake2sHasher :: HashSize -> Hasher
blake2sHasher (HashSize hashsize)
| hashsize == 256 = mkHasher blake2s_256 blake2s_256_context
| hashsize == 160 = mkHasher blake2s_160 blake2s_160_context
| hashsize == 224 = mkHasher blake2s_224 blake2s_224_context
| otherwise = error $ "unsupported BLAKE2S size " ++ show hashsize
blake2spHasher :: HashSize -> Hasher
blake2spHasher (HashSize hashsize)
| hashsize == 256 = mkHasher blake2sp_256 blake2sp_256_context
| hashsize == 224 = mkHasher blake2sp_224 blake2sp_224_context
| otherwise = error $ "unsupported BLAKE2SP size " ++ show hashsize
sha1Hasher :: Hasher
sha1Hasher = mkHasher sha1 sha1_context
md5Hasher :: Hasher
md5Hasher = mkHasher md5 md5_context
descChecksum :: String
descChecksum = "checksum"
{- A varient of the SHA256E backend, for testing that needs special keys
- that cannot collide with legitimate keys in the repository.
-
- This is accomplished by appending a special extension to the key,
- that is not one that selectExtension would select (due to being too
- long).
-}
testKeyBackend :: Backend
testKeyBackend =
let b = genBackendE (SHA2Hash (HashSize 256))
gk = case genKey b of
Nothing -> Nothing
Just f -> Just (\ks p -> addTestE <$> f ks p)
in b { genKey = gk }
where
addTestE k = alterKey k $ \d -> d
{ keyName = keyName d <> longext
}
longext = ".this-is-a-test-key"