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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 Control.Monad.State
import System.Cmd.Utils
import System.IO
import qualified Data.ByteString.Char8 as S
import qualified Data.ByteString.Lazy.Char8 as L
import Git
import Utility.SafeCommand
type CatFileHandle = (PipeHandle, Handle, Handle)
{- Starts git cat-file running in batch mode in a repo and returns a handle. -}
catFileStart :: Repo -> IO CatFileHandle
catFileStart repo = hPipeBoth "git" $ toCommand $
Git.gitCommandLine [Param "cat-file", Param "--batch"] repo
{- Stops git cat-file. -}
catFileStop :: CatFileHandle -> IO ()
catFileStop (pid, from, to) = do
hClose to
hClose from
forceSuccess pid
{- Reads a file from a specified branch. -}
catFile :: CatFileHandle -> String -> FilePath -> IO L.ByteString
catFile h branch file = catObject h (branch ++ ":" ++ file)
{- Uses a running git cat-file read the content of an object.
- Objects that do not exist will have "" returned. -}
catObject :: CatFileHandle -> String -> IO L.ByteString
catObject (_, from, to) object = do
hPutStrLn to object
hFlush to
header <- hGetLine from
case words header of
[sha, objtype, size]
| length sha == Git.shaSize &&
validobjtype objtype -> handle size
| otherwise -> empty
_
| header == object ++ " missing" -> empty
| otherwise -> error $ "unknown response from git cat-file " ++ header
where
handle size = case reads size of
[(bytes, "")] -> readcontent bytes
_ -> empty
readcontent bytes = do
content <- S.hGet from bytes
c <- hGetChar from
when (c /= '\n') $
error "missing newline from git cat-file"
return $ L.fromChunks [content]
empty = return L.empty
validobjtype t
| t == "blob" = True
| t == "commit" = True
| t == "tree" = True
| otherwise = False
|
