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Affirmer understands and acknowledges that Creative Commons is not a party to this document and has no duty or obligation with respect to this CC0 or use of the Work. filelock-0.1.0.1/Setup.hs0000644000000000000000000000005612350002001013241 0ustar0000000000000000import Distribution.Simple main = defaultMain filelock-0.1.0.1/filelock.cabal0000644000000000000000000000224612350002001014364 0ustar0000000000000000-- Initial filelock.cabal generated by cabal init. For further -- documentation, see http://haskell.org/cabal/users-guide/ name: filelock version: 0.1.0.1 synopsis: Portable interface to file locking (flock / LockFileEx) description: This package provides an interface to Windows and Unix file locking functionalities. homepage: http://github.com/takano-akio/filelock license: PublicDomain license-file: LICENSE author: Takano Akio maintainer: aljee@hyper.cx -- copyright: category: System build-type: Simple -- extra-source-files: cabal-version: >=1.10 library exposed-modules: System.FileLock other-modules: System.FileLock.Internal.Flock System.FileLock.Internal.LockFileEx -- other-extensions: build-depends: base >=4.5.1.0 && <5 -- hs-source-dirs: default-language: Haskell2010 ghc-options: -Wall if os(windows) cpp-options: -DUSE_LOCKFILEEX build-depends: Win32 else cpp-options: -DUSE_FLOCK build-depends: unix filelock-0.1.0.1/System/0000755000000000000000000000000012350002001013070 5ustar0000000000000000filelock-0.1.0.1/System/FileLock.hs0000644000000000000000000000542212350002001015117 0ustar0000000000000000{-# LANGUAGE DeriveDataTypeable #-} {-# LANGUAGE CPP #-} -- | This module provides a portable interface to file locks as a mechanism for -- inter-process synchronization. -- -- Each file lock is associated with a file. When taking a lock, the assiciated -- file is created if it's not present, then the file is locked in an -- OS-dependent way. While the lock is being held, no other process or -- thread can take it, unless the specified 'SharedExclusive' values -- allow it. -- -- All locks held by a process are released when the process exits. They can -- also be explicitly released using 'unlockFile'. -- -- It is not recommended to open or otherwise use lock files for other -- purposes, because it tends to expose differences between operating systems. -- For example, on Windows 'System.IO.openFile' for a lock file will fail when -- the lock is held, but on Unix it won't. -- -- Note on the implementation: currently the module uses flock(2) on non-Windows -- platforms, and LockFileEx on Windows. module System.FileLock ( FileLock , SharedExclusive(..) , lockFile , tryLockFile , unlockFile , withFileLock ) where import Control.Applicative import qualified Control.Exception as E import Control.Monad import Data.IORef import Data.Traversable (traverse) import Data.Typeable #ifdef USE_FLOCK import qualified System.FileLock.Internal.Flock as I #elif USE_LOCKFILEEX import qualified System.FileLock.Internal.LockFileEx as I #else #error No backend is available #endif -- | A token that represents ownership of a lock. data FileLock = Lock {-# UNPACk #-} !I.Lock {-# UNPACk #-} !(IORef Bool) -- alive? deriving (Typeable) instance Eq FileLock where Lock _ x == Lock _ y = x == y newLock :: I.Lock -> IO FileLock newLock x = Lock x <$> newIORef True -- | A type of lock to be taken. data SharedExclusive = Shared -- ^ Other process can hold a shared lock at the same time. | Exclusive -- ^ No other process can hold a lock, shared or exclusive. deriving (Show, Eq, Typeable) -- | Take a lock. This function blocks until the lock is available. lockFile :: FilePath -> SharedExclusive -> IO FileLock lockFile path mode = newLock =<< I.lock path (mode == Exclusive) -- | Try to take a lock. This function does not block. If the lock is not -- immediately available, it returns Nothing. tryLockFile :: FilePath -> SharedExclusive -> IO (Maybe FileLock) tryLockFile path mode = traverse newLock =<< I.tryLock path (mode == Exclusive) -- | Release the lock. unlockFile :: FileLock -> IO () unlockFile (Lock l ref) = do wasAlive <- atomicModifyIORef ref $ \old -> (False, old) when wasAlive $ I.unlock l -- | Perform some action with a lock held. withFileLock :: FilePath -> SharedExclusive -> (FileLock -> IO a) -> IO a withFileLock path mode = E.bracket (lockFile path mode) unlockFile filelock-0.1.0.1/System/FileLock/0000755000000000000000000000000012350002001014560 5ustar0000000000000000filelock-0.1.0.1/System/FileLock/Internal/0000755000000000000000000000000012350002001016334 5ustar0000000000000000filelock-0.1.0.1/System/FileLock/Internal/Flock.hsc0000644000000000000000000000314712350002001020076 0ustar0000000000000000module System.FileLock.Internal.Flock #ifndef USE_FLOCK () where #else (Lock, lock, tryLock, unlock) where #include import Control.Applicative import qualified Control.Exception as E import Data.Bits import Foreign.C.Error import Foreign.C.Types import System.Posix.Files import System.Posix.IO (openFd, closeFd, defaultFileFlags, OpenMode(..)) import System.Posix.Types type Lock = Fd lock :: FilePath -> Bool -> IO Lock lock path exclusive = do fd <- open path (`E.onException` closeFd fd) $ do True <- flock fd exclusive True return fd tryLock :: FilePath -> Bool -> IO (Maybe Lock) tryLock path exclusive = do fd <- open path (`E.onException` closeFd fd) $ do success <- flock fd exclusive False if success then return $ Just $ fd else Nothing <$ closeFd fd unlock :: Lock -> IO () unlock fd = closeFd fd open :: FilePath -> IO Fd open path = openFd path WriteOnly (Just stdFileMode) defaultFileFlags flock :: Fd -> Bool -> Bool -> IO Bool flock (Fd fd) exclusive block = do r <- c_flock fd $ modeOp .|. blockOp if r == 0 then return True -- success else do errno <- getErrno case () of _ | errno == eWOULDBLOCK -> return False -- already taken | errno == eINTR -> flock (Fd fd) exclusive block | otherwise -> throwErrno "flock" where modeOp = case exclusive of False -> #{const LOCK_SH} True -> #{const LOCK_EX} blockOp = case block of True -> 0 False -> #{const LOCK_NB} foreign import ccall "flock" c_flock :: CInt -> CInt -> IO CInt #endif /* USE_FLOCK */ filelock-0.1.0.1/System/FileLock/Internal/LockFileEx.hsc0000644000000000000000000000365412350002001021030 0ustar0000000000000000module System.FileLock.Internal.LockFileEx #ifndef USE_LOCKFILEEX () where #else (Lock, lock, tryLock, unlock) where #include import Control.Applicative import qualified Control.Exception as E import Data.Bits import Foreign.Marshal.Alloc import System.Win32.File import System.Win32.Mem import System.Win32.Types type Lock = HANDLE lock :: FilePath -> Bool -> IO Lock lock path exclusive = do file <- open path (`E.onException` closeHandle file) $ do True <- lockFirstByte file exclusive True return file tryLock :: FilePath -> Bool -> IO (Maybe Lock) tryLock path exclusive = do file <- open path (`E.onException` closeHandle file) $ do r <- lockFirstByte file exclusive False if r then return $ Just file else Nothing <$ closeHandle file unlock :: Lock -> IO () unlock = closeHandle open :: FilePath -> IO HANDLE open path = createFile path gENERIC_WRITE (fILE_SHARE_READ .|. fILE_SHARE_WRITE) Nothing oPEN_ALWAYS fILE_ATTRIBUTE_NORMAL Nothing lockFirstByte :: HANDLE -> Bool -> Bool -> IO Bool lockFirstByte handle exclusive block = allocaBytes sizeof_OVERLAPPED $ \op -> do zeroMemory op $ fromIntegral sizeof_OVERLAPPED -- Offset and OffsetHigh fields are set to 0 by zeroMemory. r <- c_lockFileEx handle (exFlag .|. blockFlag) 0{-reserved-} 1{-number of bytes, lower dword-} 0{-number of bytes, higher dword-} op if r then return True -- success else do code <- getLastError if code == #{const ERROR_LOCK_VIOLATION} then return False -- already taken else failWith "LockFileEx" code where exFlag = if exclusive then #{const LOCKFILE_EXCLUSIVE_LOCK} else 0 blockFlag = if block then 0 else #{const LOCKFILE_FAIL_IMMEDIATELY} sizeof_OVERLAPPED = #{size OVERLAPPED} foreign import stdcall "LockFileEx" c_lockFileEx :: HANDLE -> DWORD -> DWORD -> DWORD -> DWORD -> LPOVERLAPPED -> IO BOOL #endif /* USE_LOCKFILEEX */