git-annex/Annex/Journal.hs
Joey Hess bf86b5ca16 improve robustness of fromDirect and replaceFile
Made fromDirect check that a file in the tree has good content (and is not
a broken symlink either) before copying it to another file that has the
same key.

Made replaceFile clean up the temp file if the action that creates it, or
the file replacement action fails.
2013-05-25 15:06:02 -04:00

103 lines
3.1 KiB
Haskell

{- management of the git-annex journal
-
- The journal is used to queue up changes before they are committed to the
- git-annex branch. Amoung other things, it ensures that if git-annex is
- interrupted, its recorded data is not lost.
-
- Copyright 2011 Joey Hess <joey@kitenet.net>
-
- Licensed under the GNU GPL version 3 or higher.
-}
{-# LANGUAGE CPP #-}
module Annex.Journal where
import System.IO.Binary
import Common.Annex
import Annex.Exception
import qualified Git
import Annex.Perms
{- Records content for a file in the branch to the journal.
-
- Using the journal, rather than immediatly staging content to the index
- avoids git needing to rewrite the index after every change. -}
setJournalFile :: FilePath -> String -> Annex ()
setJournalFile file content = do
createAnnexDirectory =<< fromRepo gitAnnexJournalDir
createAnnexDirectory =<< fromRepo gitAnnexTmpDir
-- journal file is written atomically
jfile <- fromRepo $ journalFile file
tmp <- fromRepo gitAnnexTmpDir
let tmpfile = tmp </> takeFileName jfile
liftIO $ do
writeBinaryFile tmpfile content
moveFile tmpfile jfile
{- Gets any journalled content for a file in the branch. -}
getJournalFile :: FilePath -> Annex (Maybe String)
getJournalFile file = inRepo $ \g -> catchMaybeIO $
readFileStrict $ journalFile file g
{- List of files that have updated content in the journal. -}
getJournalledFiles :: Annex [FilePath]
getJournalledFiles = map fileJournal <$> getJournalFiles
{- List of existing journal files. -}
getJournalFiles :: Annex [FilePath]
getJournalFiles = do
g <- gitRepo
fs <- liftIO $ catchDefaultIO [] $
getDirectoryContents $ gitAnnexJournalDir g
return $ filter (`notElem` [".", ".."]) fs
{- Checks if there are changes in the journal. -}
journalDirty :: Annex Bool
journalDirty = not . null <$> getJournalFiles
{- Produces a filename to use in the journal for a file on the branch.
-
- The journal typically won't have a lot of files in it, so the hashing
- used in the branch is not necessary, and all the files are put directly
- in the journal directory.
-}
journalFile :: FilePath -> Git.Repo -> FilePath
journalFile file repo = gitAnnexJournalDir repo </> concatMap mangle file
where
mangle c
| c == pathSeparator = "_"
| c == '_' = "__"
| otherwise = [c]
{- Converts a journal file (relative to the journal dir) back to the
- filename on the branch. -}
fileJournal :: FilePath -> FilePath
fileJournal = replace [pathSeparator, pathSeparator] "_" .
replace "_" [pathSeparator]
{- Runs an action that modifies the journal, using locking to avoid
- contention with other git-annex processes. -}
lockJournal :: Annex a -> Annex a
lockJournal a = do
lockfile <- fromRepo gitAnnexJournalLock
createAnnexDirectory $ takeDirectory lockfile
mode <- annexFileMode
bracketIO (lock lockfile mode) unlock (const a)
where
lock lockfile mode = do
#ifndef __WINDOWS__
l <- noUmask mode $ createFile lockfile mode
waitToSetLock l (WriteLock, AbsoluteSeek, 0, 0)
return l
#else
writeFile lockfile ""
return lockfile
#endif
#ifndef __WINDOWS__
unlock = closeFd
#else
unlock = removeFile
#endif