75 lines
2 KiB
Haskell
75 lines
2 KiB
Haskell
{- git cat-file interface
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-
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- Copyright 2011 Joey Hess <joey@kitenet.net>
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-
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- Licensed under the GNU GPL version 3 or higher.
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-}
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module Git.CatFile (
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CatFileHandle,
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catFileStart,
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catFileStop,
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catFile,
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catObject,
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catObjectDetails,
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) where
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import System.IO
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import qualified Data.ByteString as S
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import qualified Data.ByteString.Lazy as L
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import Common
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import Git
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import Git.Sha
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import Git.Command
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import Git.Types
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import qualified Utility.CoProcess as CoProcess
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type CatFileHandle = CoProcess.CoProcessHandle
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catFileStart :: Repo -> IO CatFileHandle
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catFileStart = gitCoProcessStart
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[ Param "cat-file"
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, Param "--batch"
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]
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catFileStop :: CatFileHandle -> IO ()
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catFileStop = CoProcess.stop
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{- Reads a file from a specified branch. -}
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catFile :: CatFileHandle -> Branch -> FilePath -> IO L.ByteString
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catFile h branch file = catObject h $ Ref $ show branch ++ ":" ++ file
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{- Uses a running git cat-file read the content of an object.
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- Objects that do not exist will have "" returned. -}
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catObject :: CatFileHandle -> Ref -> IO L.ByteString
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catObject h object = maybe L.empty fst <$> catObjectDetails h object
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{- Gets both the content of an object, and its Sha. -}
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catObjectDetails :: CatFileHandle -> Ref -> IO (Maybe (L.ByteString, Sha))
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catObjectDetails h object = CoProcess.query h send receive
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where
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send to = do
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fileEncoding to
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hPutStrLn to $ show object
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receive from = do
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fileEncoding from
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header <- hGetLine from
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case words header of
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[sha, objtype, size]
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| length sha == shaSize &&
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isJust (readObjectType objtype) ->
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case reads size of
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[(bytes, "")] -> readcontent bytes from sha
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_ -> dne
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| otherwise -> dne
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_
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| header == show object ++ " missing" -> dne
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| otherwise -> error $ "unknown response from git cat-file " ++ show (header, object)
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readcontent bytes from sha = do
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content <- S.hGet from bytes
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c <- hGetChar from
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when (c /= '\n') $
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error "missing newline from git cat-file"
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return $ Just (L.fromChunks [content], Ref sha)
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dne = return Nothing
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