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|
{- git cat-file interface
-
- Copyright 2011 Joey Hess <joey@kitenet.net>
-
- Licensed under the GNU GPL version 3 or higher.
-}
module Git.CatFile (
CatFileHandle,
catFileStart,
catFileStop,
catFile,
catObject
) where
import System.IO
import qualified Data.ByteString.Char8 as S
import qualified Data.ByteString.Lazy.Char8 as L
import Common
import Git
import Git.Sha
import Git.Command
import qualified Utility.CoProcess as CoProcess
type CatFileHandle = CoProcess.CoProcessHandle
catFileStart :: Repo -> IO CatFileHandle
catFileStart = CoProcess.start "git" . toCommand . gitCommandLine
[ Param "cat-file"
, Param "--batch"
]
catFileStop :: CatFileHandle -> IO ()
catFileStop = CoProcess.stop
{- Reads a file from a specified branch. -}
catFile :: CatFileHandle -> Branch -> FilePath -> IO L.ByteString
catFile h branch file = catObject h $ Ref $ show branch ++ ":" ++ file
{- Uses a running git cat-file read the content of an object.
- Objects that do not exist will have "" returned. -}
catObject :: CatFileHandle -> Ref -> IO L.ByteString
catObject h object = CoProcess.query h send receive
where
send to = do
fileEncoding to
hPutStrLn to $ show object
receive from = do
fileEncoding from
header <- hGetLine from
case words header of
[sha, objtype, size]
| length sha == shaSize &&
validobjtype objtype ->
case reads size of
[(bytes, "")] -> readcontent bytes from
_ -> dne
| otherwise -> dne
_
| header == show object ++ " missing" -> dne
| otherwise -> error $ "unknown response from git cat-file " ++ show (header, object)
readcontent bytes from = do
content <- S.hGet from bytes
c <- hGetChar from
when (c /= '\n') $
error "missing newline from git cat-file"
return $ L.fromChunks [content]
dne = return L.empty
validobjtype t
| t == "blob" = True
| t == "commit" = True
| t == "tree" = True
| otherwise = False
|
