90 lines
2.7 KiB
Haskell
90 lines
2.7 KiB
Haskell
{- git-annex file locations
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-
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- Copyright 2010-2019 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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module Annex.DirHashes (
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Hasher,
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HashLevels(..),
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objectHashLevels,
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branchHashLevels,
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branchHashDir,
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dirHashes,
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hashDirMixed,
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hashDirLower,
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display_32bits_as_dir
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) where
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import Data.Default
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import Data.Bits
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import qualified Data.ByteArray as BA
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import qualified Data.ByteArray.Encoding as BA
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import qualified Data.ByteString as S
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import qualified System.FilePath.ByteString as P
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import Common
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import Key
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import Types.GitConfig
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import Types.Difference
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import Utility.Hash
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import Utility.MD5
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type Hasher = Key -> RawFilePath
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-- Number of hash levels to use. 2 is the default.
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newtype HashLevels = HashLevels Int
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instance Default HashLevels where
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def = HashLevels 2
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objectHashLevels :: GitConfig -> HashLevels
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objectHashLevels = configHashLevels OneLevelObjectHash
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branchHashLevels :: GitConfig -> HashLevels
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branchHashLevels = configHashLevels OneLevelBranchHash
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configHashLevels :: Difference -> GitConfig -> HashLevels
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configHashLevels d config
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| otherwise = def
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branchHashDir :: GitConfig -> Key -> S.ByteString
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branchHashDir = hashDirLower . branchHashLevels
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{- Two different directory hashes may be used. The mixed case hash
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- came first, and is fine, except for the problem of case-strict
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- filesystems such as Linux VFAT (mounted with shortname=mixed),
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- which do not allow using a directory "XX" when "xx" already exists.
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- To support that, some git-annex repositories use the lower case-hash.
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- All special remotes use the lower-case hash for new data, but old data
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- may still use the mixed case hash. -}
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dirHashes :: [HashLevels -> Hasher]
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dirHashes = [hashDirLower, hashDirMixed]
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hashDirs :: HashLevels -> Int -> S.ByteString -> RawFilePath
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hashDirs (HashLevels 1) sz s = P.addTrailingPathSeparator $ S.take sz s
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hashDirs _ sz s = P.addTrailingPathSeparator $ h P.</> t
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where
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(h, t) = S.splitAt sz s
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hashDirLower :: HashLevels -> Hasher
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hashDirLower n k = hashDirs n 3 $ S.pack $ take 6 $ conv $
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md5s $ serializeKey' $ nonChunkKey k
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where
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conv v = BA.unpack $
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(BA.convertToBase BA.Base16 v :: BA.Bytes)
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{- This was originally using Data.Hash.MD5 from MissingH. This new version
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- is faster, but ugly as it has to replicate the 4 Word32's that produced. -}
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hashDirMixed :: HashLevels -> Hasher
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hashDirMixed n k = hashDirs n 2 $ S.pack $ take 4 $
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concatMap display_32bits_as_dir $
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encodeWord32 $ map fromIntegral $ BA.unpack $
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Utility.Hash.md5s $ serializeKey' $ nonChunkKey k
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where
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encodeWord32 (b1:b2:b3:b4:rest) =
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(shiftL b4 24 .|. shiftL b3 16 .|. shiftL b2 8 .|. b1)
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: encodeWord32 rest
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encodeWord32 _ = []
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