git-annex/Annex/CatFile.hs
2013-12-15 14:02:23 -04:00

139 lines
4.6 KiB
Haskell

{- git cat-file interface, with handle automatically stored in the Annex monad
-
- Copyright 2011-2013 Joey Hess <joey@kitenet.net>
-
- Licensed under the GNU GPL version 3 or higher.
-}
module Annex.CatFile (
catFile,
catObject,
catTree,
catObjectDetails,
catFileHandle,
catKey,
catKeyFile,
catKeyFileHEAD,
) where
import qualified Data.ByteString.Lazy as L
import qualified Data.Map as M
import System.PosixCompat.Types
import Common.Annex
import qualified Git
import qualified Git.CatFile
import qualified Annex
import Git.Types
import Git.FilePath
import Git.FileMode
import qualified Git.Ref
catFile :: Git.Branch -> FilePath -> Annex L.ByteString
catFile branch file = do
h <- catFileHandle
liftIO $ Git.CatFile.catFile h branch file
catObject :: Git.Ref -> Annex L.ByteString
catObject ref = do
h <- catFileHandle
liftIO $ Git.CatFile.catObject h ref
catTree :: Git.Ref -> Annex [(FilePath, FileMode)]
catTree ref = do
h <- catFileHandle
liftIO $ Git.CatFile.catTree h ref
catObjectDetails :: Git.Ref -> Annex (Maybe (L.ByteString, Sha, ObjectType))
catObjectDetails ref = do
h <- catFileHandle
liftIO $ Git.CatFile.catObjectDetails h ref
{- There can be multiple index files, and a different cat-file is needed
- for each. This is selected by setting GIT_INDEX_FILE in the gitEnv. -}
catFileHandle :: Annex Git.CatFile.CatFileHandle
catFileHandle = do
m <- Annex.getState Annex.catfilehandles
indexfile <- fromMaybe "" . maybe Nothing (lookup "GIT_INDEX_FILE")
<$> fromRepo gitEnv
case M.lookup indexfile m of
Just h -> return h
Nothing -> do
h <- inRepo Git.CatFile.catFileStart
let m' = M.insert indexfile h m
Annex.changeState $ \s -> s { Annex.catfilehandles = m' }
return h
{- From the Sha or Ref of a symlink back to the key.
-
- Requires a mode witness, to guarantee that the file is a symlink.
-}
catKey :: Ref -> FileMode -> Annex (Maybe Key)
catKey = catKey' True
catKey' :: Bool -> Ref -> FileMode -> Annex (Maybe Key)
catKey' modeguaranteed ref mode
| isSymLink mode = do
l <- fromInternalGitPath . encodeW8 . L.unpack <$> get
return $ if isLinkToAnnex l
then fileKey $ takeFileName l
else Nothing
| otherwise = return Nothing
where
-- If the mode is not guaranteed to be correct, avoid
-- buffering the whole file content, which might be large.
-- 8192 is enough if it really is a symlink.
get
| modeguaranteed = catObject ref
| otherwise = L.take 8192 <$> catObject ref
{- Looks up the file mode corresponding to the Ref using the running
- cat-file.
-
- Currently this always has to look in HEAD, because cat-file --batch
- does not offer a way to specify that we want to look up a tree object
- in the index. So if the index has a file staged not as a symlink,
- and it is a symlink in head, the wrong mode is gotten.
- Also, we have to assume the file is a symlink if it's not yet committed
- to HEAD. For these reasons, modeguaranteed is not set.
-}
catKeyChecked :: Bool -> Ref -> Annex (Maybe Key)
catKeyChecked needhead ref@(Ref r) =
catKey' False ref =<< findmode <$> catTree treeref
where
pathparts = split "/" r
dir = intercalate "/" $ take (length pathparts - 1) pathparts
file = fromMaybe "" $ lastMaybe pathparts
treeref = Ref $ if needhead then "HEAD" ++ dir ++ "/" else dir ++ "/"
findmode = fromMaybe symLinkMode . headMaybe .
map snd . filter (\p -> fst p == file)
{- From a file in the repository back to the key.
-
- Ideally, this should reflect the key that's staged in the index,
- not the key that's committed to HEAD. Unfortunately, git cat-file
- does not refresh the index file after it's started up, so things
- newly staged in the index won't show up. It does, however, notice
- when branches change.
-
- For command-line git-annex use, that doesn't matter. It's perfectly
- reasonable for things staged in the index after the currently running
- git-annex process to not be noticed by it. However, we do want to see
- what's in the index, since it may have uncommitted changes not in HEAD
-
- For the assistant, this is much more of a problem, since it commits
- files and then needs to be able to immediately look up their keys.
- OTOH, the assistant doesn't keep changes staged in the index for very
- long at all before committing them -- and it won't look at the keys
- of files until after committing them.
-
- So, this gets info from the index, unless running as a daemon.
-}
catKeyFile :: FilePath -> Annex (Maybe Key)
catKeyFile f = ifM (Annex.getState Annex.daemon)
( catKeyFileHEAD f
, catKeyChecked True $ Git.Ref.fileRef f
)
catKeyFileHEAD :: FilePath -> Annex (Maybe Key)
catKeyFileHEAD f = catKeyChecked False $ Git.Ref.fileFromRef Git.Ref.headRef f