git-annex/Remote/Directory.hs

{- A "remote" that is just a filesystem directory.
 -
 - Copyright 2011-2014 Joey Hess <joey@kitenet.net>
 -
 - Licensed under the GNU GPL version 3 or higher.
 -}

{-# LANGUAGE CPP #-}

module Remote.Directory (
	remote,
	finalizeStoreGeneric,
	removeDirGeneric,
) where

import qualified Data.ByteString.Lazy as L
import qualified Data.Map as M

import Common.Annex
import Types.Remote
import Types.Creds
import qualified Git
import Config.Cost
import Config
import Utility.FileMode
import Remote.Helper.Special
import qualified Remote.Directory.LegacyChunked as Legacy
import Annex.Content
import Annex.UUID
import Utility.Metered

remote :: RemoteType
remote = RemoteType {
	typename = "directory",
	enumerate = findSpecialRemotes "directory",
	generate = gen,
	setup = directorySetup
}

gen :: Git.Repo -> UUID -> RemoteConfig -> RemoteGitConfig -> Annex (Maybe Remote)
gen r u c gc = do
	cst <- remoteCost gc cheapRemoteCost
	let chunkconfig = getChunkConfig c
	return $ Just $ specialRemote c
		(prepareStore dir chunkconfig)
		(retrieve dir chunkconfig)
		(simplyPrepare $ remove dir)
		(simplyPrepare $ checkKey dir chunkconfig)
		Remote {
			uuid = u,
			cost = cst,
			name = Git.repoDescribe r,
			storeKey = storeKeyDummy,
			retrieveKeyFile = retreiveKeyFileDummy,
			retrieveKeyFileCheap = retrieveCheap dir chunkconfig,
			removeKey = removeKeyDummy,
			checkPresent = checkPresentDummy,
			checkPresentCheap = True,
			whereisKey = Nothing,
			remoteFsck = Nothing,
			repairRepo = Nothing,
			config = c,
			repo = r,
			gitconfig = gc,
			localpath = Just dir,
			readonly = False,
			availability = LocallyAvailable,
			remotetype = remote
		}
  where
	dir = fromMaybe (error "missing directory") $ remoteAnnexDirectory gc

directorySetup :: Maybe UUID -> Maybe CredPair -> RemoteConfig -> Annex (RemoteConfig, UUID)
directorySetup mu _ c = do
	u <- maybe (liftIO genUUID) return mu
	-- verify configuration is sane
	let dir = fromMaybe (error "Specify directory=") $
		M.lookup "directory" c
	absdir <- liftIO $ absPath dir
	liftIO $ unlessM (doesDirectoryExist absdir) $
		error $ "Directory does not exist: " ++ absdir
	c' <- encryptionSetup c

	-- The directory is stored in git config, not in this remote's
	-- persistant state, so it can vary between hosts.
	gitConfigSpecialRemote u c' "directory" absdir
	return (M.delete "directory" c', u)

{- Locations to try to access a given Key in the directory.
 - We try more than one since we used to write to different hash
 - directories. -}
locations :: FilePath -> Key -> [FilePath]
locations d k = map (d </>) (keyPaths k)

{- Returns the location off a Key in the directory. If the key is
 - present, returns the location that is actually used, otherwise
 - returns the first, default location. -}
getLocation :: FilePath -> Key -> IO FilePath
getLocation d k = do
	let locs = locations d k
	fromMaybe (Prelude.head locs) <$> firstM doesFileExist locs

{- Directory where the file(s) for a key are stored. -}
storeDir :: FilePath -> Key -> FilePath
storeDir d k = addTrailingPathSeparator $ d </> hashDirLower k </> keyFile k

{- Where we store temporary data for a key, in the directory, as it's being
 - written. -}
tmpDir :: FilePath -> Key -> FilePath
tmpDir d k = addTrailingPathSeparator $ d </> "tmp" </> keyFile k

{- Check if there is enough free disk space in the remote's directory to
 - store the key. Note that the unencrypted key size is checked. -}
prepareStore :: FilePath -> ChunkConfig -> Preparer Storer
prepareStore d chunkconfig = checkPrepare
	(\k -> checkDiskSpace (Just d) k 0)
	(byteStorer $ store d chunkconfig)

store :: FilePath -> ChunkConfig -> Key -> L.ByteString -> MeterUpdate -> Annex Bool
store d chunkconfig k b p = liftIO $ do
	void $ tryIO $ createDirectoryIfMissing True tmpdir
	case chunkconfig of
		LegacyChunks chunksize -> Legacy.store chunksize finalizeStoreGeneric k b p tmpdir destdir
		_ -> do
			let tmpf = tmpdir </> keyFile k
			meteredWriteFile p tmpf b
			finalizeStoreGeneric tmpdir destdir
			return True
  where
	tmpdir = tmpDir d k
	destdir = storeDir d k

{- Passed a temp directory that contains the files that should be placed
 - in the dest directory, moves it into place. Anything already existing
 - in the dest directory will be deleted. File permissions will be locked
 - down. -}
finalizeStoreGeneric :: FilePath -> FilePath -> IO ()
finalizeStoreGeneric tmp dest = do
	void $ tryIO $ allowWrite dest -- may already exist
	void $ tryIO $ removeDirectoryRecursive dest -- or not exist
	createDirectoryIfMissing True (parentDir dest)
	renameDirectory tmp dest
	-- may fail on some filesystems
	void $ tryIO $ do
		mapM_ preventWrite =<< dirContents dest
		preventWrite dest

retrieve :: FilePath -> ChunkConfig -> Preparer Retriever
retrieve d (LegacyChunks _) = Legacy.retrieve locations d
retrieve d _ = simplyPrepare $ byteRetriever $ \k sink ->
	sink =<< liftIO (L.readFile =<< getLocation d k)

retrieveCheap :: FilePath -> ChunkConfig -> Key -> FilePath -> Annex Bool
-- no cheap retrieval possible for chunks
retrieveCheap _ (UnpaddedChunks _) _ _ = return False
retrieveCheap _ (LegacyChunks _) _ _ = return False
#ifndef mingw32_HOST_OS
retrieveCheap d NoChunks k f = liftIO $ catchBoolIO $ do
	file <- getLocation d k
	createSymbolicLink file f
	return True
#else
retrieveCheap _ _ _ _ = return False
#endif

remove :: FilePath -> Remover
remove d k = liftIO $ removeDirGeneric d (storeDir d k)

{- Removes the directory, which must be located under the topdir.
 -
 - Succeeds even on directories and contents that do not have write
 - permission.
 -
 - If the directory does not exist, succeeds as long as the topdir does
 - exist. If the topdir does not exist, fails, because in this case the
 - remote is not currently accessible and probably still has the content
 - we were supposed to remove from it.
 -}
removeDirGeneric :: FilePath -> FilePath -> IO Bool
removeDirGeneric topdir dir = do
	void $ tryIO $ allowWrite dir
#ifdef mingw32_HOST_OS
	{- Windows needs the files inside the directory to be writable
	 - before it can delete them. -}
	void $ tryIO $ mapM_ allowWrite =<< dirContents dir
#endif
	ok <- catchBoolIO $ do
		removeDirectoryRecursive dir
		return True
	if ok
		then return ok
		else doesDirectoryExist topdir <&&> (not <$> doesDirectoryExist dir)

checkKey :: FilePath -> ChunkConfig -> CheckPresent
checkKey d (LegacyChunks _) k = Legacy.checkKey d locations k
checkKey d _ k = liftIO $
	ifM (anyM doesFileExist (locations d k))
		( return True
		, error $ "directory " ++ d ++ " is not accessible"
		)