remove checksum from WORM
with size and mtime in the key, it's redundant
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2 changed files with 9 additions and 18 deletions
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@ -6,7 +6,6 @@ module Backend.WORM (backend) where
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import Control.Monad.State
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import System.FilePath
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import System.Posix.Files
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import Data.Digest.Pure.SHA -- slow, but we only checksum filenames
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import qualified Data.ByteString.Lazy.Char8 as B
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import qualified Backend.File
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@ -18,25 +17,18 @@ backend = Backend.File.backend {
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getKey = keyValue
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}
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-- A SHA1 of the basename of the filename, plus the file size and
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-- modification time, is used as the unique part of the key. That
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-- allows multiple files with the same names to have different keys,
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-- The key is formed from the file size, modification time, and the
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-- basename of the filename.
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--
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-- That allows multiple files with the same names to have different keys,
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-- while also allowing a file to be moved around while retaining the
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-- same key.
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--
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-- The file size and modification time are also included in the key,
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-- unhashed. This could be used as a sanity check.
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--
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-- The basename of the filename is also included in the key, so it's clear
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-- what the original filename was when a user sees the value.
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keyValue :: FilePath -> Annex (Maybe Key)
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keyValue file = do
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stat <- liftIO $ getFileStatus file
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return $ Just $ Key ((name backend), key stat)
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where
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key stat = (checksum $ uniqueid stat) ++ sep ++
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uniqueid stat ++ sep ++ base
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checksum s = show $ sha1 $ B.pack s
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key stat = uniqueid stat ++ sep ++ base
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uniqueid stat = (show $ modificationTime stat) ++ sep ++
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(show $ fileSize stat)
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base = takeFileName file
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