64 lines
1.6 KiB
Haskell
64 lines
1.6 KiB
Haskell
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{- 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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) where
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import Control.Monad.State
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import System.Cmd.Utils
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import System.IO
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import qualified Data.ByteString.Char8 as B
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import Git
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import Utility.SafeCommand
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type CatFileHandle = (PipeHandle, Handle, Handle)
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{- Starts git cat-file running in batch mode in a repo and returns a handle. -}
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catFileStart :: Repo -> IO CatFileHandle
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catFileStart repo = hPipeBoth "git" $ toCommand $
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Git.gitCommandLine repo [Param "cat-file", Param "--batch"]
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{- Stops git cat-file. -}
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catFileStop :: CatFileHandle -> IO ()
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catFileStop (pid, from, to) = do
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hClose to
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hClose from
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forceSuccess pid
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{- Uses a running git cat-file read the content of a file from a branch.
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- Files that do not exist on the branch will have "" returned. -}
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catFile :: CatFileHandle -> String -> FilePath -> IO String
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catFile (_, from, to) branch file = do
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hPutStrLn to want
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hFlush to
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header <- hGetLine from
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case words header of
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[sha, blob, size]
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| length sha == Git.shaSize &&
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blob == "blob" -> handle size
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| otherwise -> empty
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_
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| header == want ++ " missing" -> empty
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| otherwise -> error $ "unknown response from git cat-file " ++ header
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where
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want = branch ++ ":" ++ file
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handle size = case reads size of
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[(bytes, "")] -> readcontent bytes
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_ -> empty
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readcontent bytes = do
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content <- B.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 $ B.unpack content
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empty = return ""
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