5e4deb3620
Git will eventually switch to sha2 and there will not be one single shaSize anymore, but two (40 and 64). Changed all parsers for git plumbing output to support both sizes of shas. One potential problem this does not deal with is, if somewhere in git-annex it reads two shas from different sources, and compares them to see if they're the same sha, it would fail if they're sha1 and sha256 of the same value. I don't know if that will really be a concern.
258 lines
8.3 KiB
Haskell
258 lines
8.3 KiB
Haskell
{- git cat-file interface
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-
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- Copyright 2011-2019 Joey Hess <id@joeyh.name>
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-
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- Licensed under the GNU AGPL 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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catFileStart',
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catFileStop,
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catFile,
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catFileDetails,
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catTree,
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catCommit,
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catObject,
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catObjectDetails,
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catObjectMetaData,
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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 qualified Data.ByteString.Lazy.Char8 as L8
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import qualified Data.Map as M
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import Data.String
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import Data.Char
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import Numeric
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import System.Posix.Types
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import Text.Read
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import Common
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import Git
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import Git.Sha
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import qualified Git.Ref
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import Git.Command
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import Git.Types
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import Git.FilePath
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import Git.HashObject
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import qualified Utility.CoProcess as CoProcess
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import Utility.Tuple
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data CatFileHandle = CatFileHandle
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{ catFileProcess :: CoProcess.CoProcessHandle
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, checkFileProcess :: CoProcess.CoProcessHandle
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, gitRepo :: Repo
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}
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catFileStart :: Repo -> IO CatFileHandle
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catFileStart = catFileStart' True
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catFileStart' :: Bool -> Repo -> IO CatFileHandle
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catFileStart' restartable repo = CatFileHandle
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<$> startp "--batch"
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<*> startp "--batch-check=%(objectname) %(objecttype) %(objectsize)"
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<*> pure repo
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where
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startp p = gitCoProcessStart restartable
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[ Param "cat-file"
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, Param p
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] repo
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catFileStop :: CatFileHandle -> IO ()
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catFileStop h = do
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CoProcess.stop (catFileProcess h)
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CoProcess.stop (checkFileProcess h)
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{- Reads a file from a specified branch. -}
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catFile :: CatFileHandle -> Branch -> RawFilePath -> IO L.ByteString
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catFile h branch file = catObject h $ Ref $
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fromRef branch ++ ":" ++ fromRawFilePath (toInternalGitPath file)
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catFileDetails :: CatFileHandle -> Branch -> RawFilePath -> IO (Maybe (L.ByteString, Sha, ObjectType))
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catFileDetails h branch file = catObjectDetails h $ Ref $
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fromRef branch ++ ":" ++ fromRawFilePath (toInternalGitPath 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 fst3 <$> catObjectDetails h object
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catObjectDetails :: CatFileHandle -> Ref -> IO (Maybe (L.ByteString, Sha, ObjectType))
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catObjectDetails h object = query (catFileProcess h) object newlinefallback $ \from -> do
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header <- hGetLine from
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case parseResp object header of
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Just (ParsedResp sha size objtype) -> do
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content <- S.hGet from (fromIntegral size)
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eatchar '\n' from
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return $ Just (L.fromChunks [content], sha, objtype)
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Just DNE -> return Nothing
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Nothing -> error $ "unknown response from git cat-file " ++ show (header, object)
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where
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eatchar expected from = do
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c <- hGetChar from
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when (c /= expected) $
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error $ "missing " ++ (show expected) ++ " from git cat-file"
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-- Slow fallback path for filenames containing newlines.
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newlinefallback = queryObjectType object (gitRepo h) >>= \case
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Nothing -> return Nothing
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Just objtype -> queryContent object (gitRepo h) >>= \case
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Nothing -> return Nothing
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Just content -> do
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-- only the --batch interface allows getting
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-- the sha, so have to re-hash the object
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sha <- hashObject' objtype
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(flip L.hPut content)
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(gitRepo h)
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return (Just (content, sha, objtype))
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{- Gets the size and type of an object, without reading its content. -}
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catObjectMetaData :: CatFileHandle -> Ref -> IO (Maybe (Sha, FileSize, ObjectType))
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catObjectMetaData h object = query (checkFileProcess h) object newlinefallback $ \from -> do
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resp <- hGetLine from
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case parseResp object resp of
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Just (ParsedResp sha size objtype) ->
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return $ Just (sha, size, objtype)
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Just DNE -> return Nothing
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Nothing -> error $ "unknown response from git cat-file " ++ show (resp, object)
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where
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-- Slow fallback path for filenames containing newlines.
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newlinefallback = do
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sha <- Git.Ref.sha object (gitRepo h)
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sz <- querySize object (gitRepo h)
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objtype <- queryObjectType object (gitRepo h)
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return $ (,,) <$> sha <*> sz <*> objtype
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data ParsedResp = ParsedResp Sha FileSize ObjectType | DNE
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query :: CoProcess.CoProcessHandle -> Ref -> IO a -> (Handle -> IO a) -> IO a
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query hdl object newlinefallback receive
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-- git cat-file --batch uses a line based protocol, so when the
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-- filename itself contains a newline, have to fall back to another
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-- method of getting the information.
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| '\n' `elem` s = newlinefallback
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-- git strips carriage return from the end of a line, out of some
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-- misplaced desire to support windows, so also use the newline
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-- fallback for those.
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| "\r" `isSuffixOf` s = newlinefallback
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| otherwise = CoProcess.query hdl send receive
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where
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send to = hPutStrLn to s
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s = fromRef object
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parseResp :: Ref -> String -> Maybe ParsedResp
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parseResp object l
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| " missing" `isSuffixOf` l -- less expensive than full check
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&& l == fromRef object ++ " missing" = Just DNE
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| otherwise = case words l of
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[sha, objtype, size] -> case extractSha sha of
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Just sha' -> case (readObjectType (encodeBS objtype), reads size) of
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(Just t, [(bytes, "")]) ->
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Just $ ParsedResp sha' bytes t
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_ -> Nothing
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Nothing -> Nothing
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_ -> Nothing
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querySingle :: CommandParam -> Ref -> Repo -> (Handle -> IO a) -> IO (Maybe a)
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querySingle o r repo reader = assertLocal repo $
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-- In non-batch mode, git cat-file warns on stderr when
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-- asked for an object that does not exist.
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-- Squelch that warning to behave the same as batch mode.
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withNullHandle $ \nullh -> do
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let p = gitCreateProcess
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[ Param "cat-file"
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, o
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, Param (fromRef r)
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] repo
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let p' = p
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{ std_err = UseHandle nullh
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, std_in = Inherit
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, std_out = CreatePipe
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}
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pid <- createProcess p'
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let h = stdoutHandle pid
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output <- reader h
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hClose h
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ifM (checkSuccessProcess (processHandle pid))
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( return (Just output)
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, return Nothing
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)
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querySize :: Ref -> Repo -> IO (Maybe FileSize)
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querySize r repo = maybe Nothing (readMaybe . takeWhile (/= '\n'))
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<$> querySingle (Param "-s") r repo hGetContentsStrict
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queryObjectType :: Ref -> Repo -> IO (Maybe ObjectType)
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queryObjectType r repo = maybe Nothing (readObjectType . encodeBS . takeWhile (/= '\n'))
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<$> querySingle (Param "-t") r repo hGetContentsStrict
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queryContent :: Ref -> Repo -> IO (Maybe L.ByteString)
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queryContent r repo = fmap (\b -> L.fromChunks [b])
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<$> querySingle (Param "-p") r repo S.hGetContents
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{- Gets a list of files and directories in a tree. (Not recursive.) -}
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catTree :: CatFileHandle -> Ref -> IO [(FilePath, FileMode)]
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catTree h treeref = go <$> catObjectDetails h treeref
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where
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go (Just (b, _, TreeObject)) = parsetree [] b
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go _ = []
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parsetree c b = case L.break (== 0) b of
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(modefile, rest)
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| L.null modefile -> c
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| otherwise -> parsetree
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(parsemodefile modefile:c)
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(dropsha rest)
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-- these 20 bytes after the NUL hold the file's sha
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dropsha = L.drop 21
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parsemodefile b =
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let (modestr, file) = separate (== ' ') (decodeBL b)
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in (file, readmode modestr)
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readmode = fromMaybe 0 . fmap fst . headMaybe . readOct
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catCommit :: CatFileHandle -> Ref -> IO (Maybe Commit)
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catCommit h commitref = go <$> catObjectDetails h commitref
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where
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go (Just (b, _, CommitObject)) = parseCommit b
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go _ = Nothing
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parseCommit :: L.ByteString -> Maybe Commit
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parseCommit b = Commit
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<$> (extractSha . L8.unpack =<< field "tree")
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<*> Just (maybe [] (mapMaybe (extractSha . L8.unpack)) (fields "parent"))
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<*> (parsemetadata <$> field "author")
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<*> (parsemetadata <$> field "committer")
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<*> Just (L8.unpack $ L.intercalate (L.singleton nl) message)
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where
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field n = headMaybe =<< fields n
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fields n = M.lookup (fromString n) fieldmap
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fieldmap = M.fromListWith (++) ((map breakfield) header)
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breakfield l =
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let (k, sp_v) = L.break (== sp) l
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in (k, [L.drop 1 sp_v])
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(header, message) = separate L.null ls
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ls = L.split nl b
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-- author and committer lines have the form: "name <email> date"
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-- The email is always present, even if empty "<>"
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parsemetadata l = CommitMetaData
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{ commitName = whenset $ L.init name_sp
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, commitEmail = whenset email
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, commitDate = whenset $ L.drop 2 gt_sp_date
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}
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where
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(name_sp, rest) = L.break (== lt) l
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(email, gt_sp_date) = L.break (== gt) (L.drop 1 rest)
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whenset v
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| L.null v = Nothing
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| otherwise = Just (L8.unpack v)
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nl = fromIntegral (ord '\n')
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sp = fromIntegral (ord ' ')
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lt = fromIntegral (ord '<')
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gt = fromIntegral (ord '>')
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