git-annex/Annex/LockFile.hs
Joey Hess e213ef310f git-annex (5.20140717) unstable; urgency=high
* Fix minor FD leak in journal code. Closes: #754608
  * direct: Fix handling of case where a work tree subdirectory cannot
    be written to due to permissions.
  * migrate: Avoid re-checksumming when migrating from hashE to hash backend.
  * uninit: Avoid failing final removal in some direct mode repositories
    due to file modes.
  * S3: Deal with AWS ACL configurations that do not allow creating or
    checking the location of a bucket, but only reading and writing content to
    it.
  * resolvemerge: New plumbing command that runs the automatic merge conflict
    resolver.
  * Deal with change in git 2.0 that made indirect mode merge conflict
    resolution leave behind old files.
  * sync: Fix git sync with local git remotes even when they don't have an
    annex.uuid set. (The assistant already did so.)
  * Set gcrypt-publish-participants when setting up a gcrypt repository,
    to avoid unncessary passphrase prompts.
    This is a security/usability tradeoff. To avoid exposing the gpg key
    ids who can decrypt the repository, users can unset
    gcrypt-publish-participants.
  * Install nautilus hooks even when ~/.local/share/nautilus/ does not yet
    exist, since it is not automatically created for Gnome 3 users.
  * Windows: Move .vbs files out of git\bin, to avoid that being in the
    PATH, which caused some weird breakage. (Thanks, divB)
  * Windows: Fix locking issue that prevented the webapp starting
    (since 5.20140707).

# imported from the archive
2014-07-17 11:27:25 -04:00

87 lines
2.2 KiB
Haskell

{- git-annex lock files.
-
- Copyright 2012, 2014 Joey Hess <joey@kitenet.net>
-
- Licensed under the GNU GPL version 3 or higher.
-}
{-# LANGUAGE CPP #-}
module Annex.LockFile (
lockFileShared,
unlockFile,
getLockPool,
withExclusiveLock,
) where
import Common.Annex
import Annex
import Types.LockPool
import qualified Git
import Annex.Exception
import Annex.Perms
import qualified Data.Map as M
#ifdef mingw32_HOST_OS
import Utility.WinLock
#endif
{- Create a specified lock file, and takes a shared lock, which is retained
- in the pool. -}
lockFileShared :: FilePath -> Annex ()
lockFileShared file = go =<< fromLockPool file
where
go (Just _) = noop -- already locked
go Nothing = do
#ifndef mingw32_HOST_OS
mode <- annexFileMode
lockhandle <- liftIO $ noUmask mode $
openFd file ReadOnly (Just mode) defaultFileFlags
liftIO $ waitToSetLock lockhandle (ReadLock, AbsoluteSeek, 0, 0)
#else
lockhandle <- liftIO $ waitToLock $ lockShared file
#endif
changeLockPool $ M.insert file lockhandle
unlockFile :: FilePath -> Annex ()
unlockFile file = maybe noop go =<< fromLockPool file
where
go lockhandle = do
#ifndef mingw32_HOST_OS
liftIO $ closeFd lockhandle
#else
liftIO $ dropLock lockhandle
#endif
changeLockPool $ M.delete file
getLockPool :: Annex LockPool
getLockPool = getState lockpool
fromLockPool :: FilePath -> Annex (Maybe LockHandle)
fromLockPool file = M.lookup file <$> getLockPool
changeLockPool :: (LockPool -> LockPool) -> Annex ()
changeLockPool a = do
m <- getLockPool
changeState $ \s -> s { lockpool = a m }
{- Runs an action with an exclusive lock held. If the lock is already
- held, blocks until it becomes free. -}
withExclusiveLock :: (Git.Repo -> FilePath) -> Annex a -> Annex a
withExclusiveLock getlockfile a = do
lockfile <- fromRepo getlockfile
createAnnexDirectory $ takeDirectory lockfile
mode <- annexFileMode
bracketIO (lock lockfile mode) unlock (const a)
where
#ifndef mingw32_HOST_OS
lock lockfile mode = do
l <- noUmask mode $ createFile lockfile mode
waitToSetLock l (WriteLock, AbsoluteSeek, 0, 0)
return l
unlock = closeFd
#else
lock lockfile _mode = waitToLock $ lockExclusive lockfile
unlock = dropLock
#endif