diff --git a/LICENSE b/LICENSE new file mode 100644 --- /dev/null +++ b/LICENSE @@ -0,0 +1,52 @@ +SPDX-License-Identifier: GPL-2.0-or-later AND BSD-3-Clause + +Copyright (c) 2019 Oleg Grenrus + + This library is free software: you may copy, redistribute and/or modify it + under the terms of the GNU General Public License as published by the + Free Software Foundation, either version 3 of the License, or (at your + option) any later version. + + This library is distributed in the hope that it will be useful, but + WITHOUT ANY WARRANTY; without even the implied warranty of + MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU + General Public License for more details. + + You should have received a copy of the GNU General Public License + along with this program (see `LICENSE.GPLv3`). 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You may copy and distribute verbatim copies of the Program's +source code as you receive it, in any medium, provided that you +conspicuously and appropriately publish on each copy an appropriate +copyright notice and disclaimer of warranty; keep intact all the +notices that refer to this License and to the absence of any warranty; +and give any other recipients of the Program a copy of this License +along with the Program. + +You may charge a fee for the physical act of transferring a copy, and +you may at your option offer warranty protection in exchange for a fee. + + 2. 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See the + GNU General Public License for more details. + + You should have received a copy of the GNU General Public License along + with this program; if not, write to the Free Software Foundation, Inc., + 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA. + +Also add information on how to contact you by electronic and paper mail. + +If the program is interactive, make it output a short notice like this +when it starts in an interactive mode: + + Gnomovision version 69, Copyright (C) year name of author + Gnomovision comes with ABSOLUTELY NO WARRANTY; for details type `show w'. + This is free software, and you are welcome to redistribute it + under certain conditions; type `show c' for details. + +The hypothetical commands `show w' and `show c' should show the appropriate +parts of the General Public License. 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If your program is a subroutine library, you +may consider it more useful to permit linking proprietary applications with +the library. If this is what you want to do, use the GNU Lesser General +Public License instead of this License. But first, please read +. + + + + diff --git a/cbits/windows.c b/cbits/windows.c new file mode 100644 --- /dev/null +++ b/cbits/windows.c @@ -0,0 +1,30 @@ +#include + +// from https://github.com/ghc/ghc/blob/4b431f334018eaef2cf36de3316025c68c922915/utils/fs/fs.c +HANDLE *fdOpen(LPCWSTR filename) { + // Construct access mode. + // https://docs.microsoft.com/en-us/windows/win32/fileio/file-access-rights-constants + DWORD dwDesiredAccess = GENERIC_WRITE | GENERIC_READ; + + // Construct shared mode. + // https://docs.microsoft.com/en-us/windows/win32/fileio/file-attribute-constants + DWORD dwShareMode = FILE_SHARE_READ | FILE_SHARE_WRITE; + + // Create file disposition. + // https://docs.microsoft.com/en-us/windows/win32/api/fileapi/nf-fileapi-createfilew + DWORD dwCreationDisposition = OPEN_ALWAYS; + + // Set file access attributes. + DWORD dwFlagsAndAttributes = FILE_ATTRIBUTE_NORMAL; + + SECURITY_ATTRIBUTES securityAttributes; + ZeroMemory (&securityAttributes, sizeof(SECURITY_ATTRIBUTES)); + securityAttributes.bInheritHandle = TRUE; // not sure what should be here + securityAttributes.lpSecurityDescriptor = NULL; + securityAttributes.nLength = sizeof(SECURITY_ATTRIBUTES); + + HANDLE res = CreateFileW(filename, dwDesiredAccess, dwShareMode, &securityAttributes, + dwCreationDisposition, dwFlagsAndAttributes, NULL); + + return res; +} diff --git a/lukko.cabal b/lukko.cabal new file mode 100644 --- /dev/null +++ b/lukko.cabal @@ -0,0 +1,153 @@ +cabal-version: 2.2 +name: lukko +version: 0.1 +synopsis: File locking +category: System, Concurrency +description: + This package provides access to platform dependent file locking APIs: + . + * Open file descriptor locking on Linux ("Lukko.OFD") + * @flock@ locking on unix platforms ("Lukko.FLock") + * Windows locking @LockFileEx@ ("Lukko.Windows") + * No-op locking, which throws exceptions ("Lukko.NoOp") + * "Lukko" module exports the best option for the target platform with uniform API. + . + There are alternative file locking packages: + . + * "GHC.IO.Handle.Lock" in @base >= 4.10@ is good enough for most use cases. + However, uses only 'Handle's so these locks cannot be used for intra-process locking. + (You should use e.g. 'MVar' in addition). + . + * doesn't support OFD locking. + . + /Lukko/ means lock in Finnish. + . + Submodules "Lukko.OFD", "Lukko.Windows" etc are available based on following conditions. + . + @ + if os(windows) + \ cpp-options: -DHAS_WINDOWS_LOCK + . + elif (os(linux) && flag(ofd-locking)) + \ cpp-options: -DHAS_OFD_LOCKING + \ cpp-options: -DHAS_FLOCK + . + elif !(os(solaris) || os(aix)) + \ cpp-options: -DHAS_FLOCK + @ + . + "Lukko.FLock" is available on not (Windows or Solaris or AIX). + "Lukko.NoOp" is always available. + +maintainer: Oleg Grenrus +license: GPL-2.0-or-later AND BSD-3-Clause +license-files: LICENSE LICENSE.GPLv2 LICENSE.GPLv3 +build-type: Simple +tested-with: + GHC ==7.6.3 + || ==7.8.4 + || ==7.10.3 + || ==8.0.2 + || ==8.2.2 + || ==8.4.4 + || ==8.6.5 + || ==8.8.1 + +source-repository head + type: git + location: https://github.com/phadej/lukko/ + +flag ofd-locking + default: True + manual: True + description: + Enable open file descriptor locking. Available on Linux (kernel 3.15, released Jun 8, 2014). + +library + default-language: Haskell2010 + hs-source-dirs: src + build-depends: base >=4.5 && <4.14 + build-tool-depends: hsc2hs:hsc2hs >=0.67 && <0.69 + + -- Main library module + exposed-modules: + Lukko + Lukko.NoOp + + if os(windows) + hs-source-dirs: src-windows + cpp-options: -DUSE_WINDOWS_LOCK + exposed-modules: Lukko.Windows + c-sources: cbits/windows.c + + elif (os(linux) && flag(ofd-locking)) + hs-source-dirs: src-ofd + hs-source-dirs: src-flock + hs-source-dirs: src-unix + cpp-options: -DUSE_OFD_LOCKING + exposed-modules: Lukko.OFD + + elif !(os(solaris) || os(aix)) + hs-source-dirs: src-flock + hs-source-dirs: src-unix + cpp-options: -DUSE_FLOCK + + else + hs-source-dirs: src-unix + cpp-options: -DUSE_NOOP + + -- Cabal check is silly + if (!os(windows) && !(os(solaris) || os(aix))) + exposed-modules: Lukko.FLock + + other-modules: + Lukko.Internal.FD + Lukko.Internal.FillBytes + Lukko.Internal.HandleToFD + Lukko.Internal.Types + +test-suite test-thread + default-language: Haskell2010 + type: exitcode-stdio-1.0 + hs-source-dirs: test + main-is: Tests.hs + ghc-options: -threaded + build-depends: + , async ^>=2.2.2 + , base + , filepath ^>=1.3.0.0 || ^>=1.4.0.0 + , lukko + , tasty ^>=1.2.3 + , tasty-hunit ^>=0.10.0.2 + , temporary ^>=1.3 + + if os(windows) + cpp-options: -DHAS_WINDOWS_LOCK + + elif (os(linux) && flag(ofd-locking)) + cpp-options: -DHAS_OFD_LOCKING + cpp-options: -DHAS_FLOCK + + elif !(os(solaris) || os(aix)) + cpp-options: -DHAS_FLOCK + +test-suite test-process + default-language: Haskell2010 + type: exitcode-stdio-1.0 + hs-source-dirs: test + main-is: TestProcess.hs + ghc-options: -threaded + build-depends: + , base + , bytestring >=0.9.2.1 && <0.11 + , lukko + + if os(windows) + cpp-options: -DHAS_WINDOWS_LOCK + + elif (os(linux) && flag(ofd-locking)) + cpp-options: -DHAS_OFD_LOCKING + cpp-options: -DHAS_FLOCK + + elif !(os(solaris) || os(aix)) + cpp-options: -DHAS_FLOCK diff --git a/src-flock/Lukko/FLock.hsc b/src-flock/Lukko/FLock.hsc new file mode 100644 --- /dev/null +++ b/src-flock/Lukko/FLock.hsc @@ -0,0 +1,118 @@ +{-# LANGUAGE InterruptibleFFI #-} +{-# LANGUAGE CPP #-} +{-# LANGUAGE Trustworthy #-} +-- | File locking via POSIX @flock@. +module Lukko.FLock ( + -- * Types + FileLockingNotSupported(..), + fileLockingSupported, + FileLockingMethod (..), + fileLockingMethod, + LockMode(..), + -- * File descriptors + FD, + fdOpen, + fdClose, + fdLock, + fdTryLock, + fdUnlock, + -- * Handles + hLock, + hTryLock, + hUnlock, + ) where + +#include + +import Control.Monad (void) +import System.IO (Handle) + +import Data.Bits +import Data.Function +import Foreign.C.Error +import Foreign.C.Types +import GHC.Base +import GHC.IO.Exception + +import Lukko.Internal.FD +import Lukko.Internal.Types + +------------------------------------------------------------------------------- +-- Support constants +------------------------------------------------------------------------------- + +-- | A constants specifying whether file locking is supported. +fileLockingSupported :: Bool +fileLockingSupported = True + +-- | A constant specifying this method +fileLockingMethod :: FileLockingMethod +fileLockingMethod = MethodFLock + +------------------------------------------------------------------------------- +-- FD +------------------------------------------------------------------------------- + +-- | Lock using OFD locks. +fdLock :: FD -> LockMode -> IO () +fdLock fd mode = void (lockImpl Nothing fd "fdLock" mode True) + +-- | Try to lock using OFD locks. +fdTryLock :: FD -> LockMode -> IO Bool +fdTryLock fd mode = lockImpl Nothing fd "fdTryLock" mode False + +-- | Unlock using OFD locks. +fdUnlock :: FD -> IO () +fdUnlock = unlockImpl + +------------------------------------------------------------------------------- +-- Handle +------------------------------------------------------------------------------- + +-- | Lock using OFD locks. +hLock :: Handle -> LockMode -> IO () +hLock h mode = do + fd <- handleToFd h + void (lockImpl (Just h) fd "hLock" mode True) + +-- | Try to lock using OFD locks. +hTryLock :: Handle -> LockMode -> IO Bool +hTryLock h mode = do + fd <- handleToFd h + lockImpl (Just h) fd "hTryLock" mode False + +-- | Unlock using OFD locks. +hUnlock :: Handle -> IO () +hUnlock h = do + fd <- handleToFd h + unlockImpl fd + +------------------------------------------------------------------------------- +-- Compat stuff +------------------------------------------------------------------------------- + +------------------------------------------------------------------------------- +-- implementation +------------------------------------------------------------------------------- + +lockImpl :: Maybe Handle -> FD -> String -> LockMode -> Bool -> IO Bool +lockImpl mh (FD fd) ctx mode block = do + let flags = cmode .|. (if block then 0 else #{const LOCK_NB}) + fix $ \retry -> c_flock fd flags >>= \res -> case res of + 0 -> return True + _ -> getErrno >>= \errno -> case () of + _ | not block + , errno == eAGAIN || errno == eACCES -> return False + | errno == eINTR -> retry + | otherwise -> ioException $ errnoToIOError ctx errno mh Nothing + where + cmode = case mode of + SharedLock -> #{const LOCK_SH} + ExclusiveLock -> #{const LOCK_EX} + +unlockImpl :: FD -> IO () +unlockImpl (FD fd) = do + throwErrnoIfMinus1_ "flock" $ c_flock fd #{const LOCK_UN} + +foreign import ccall interruptible "flock" + c_flock :: CInt -> CInt -> IO CInt diff --git a/src-ofd/Lukko/OFD.hsc b/src-ofd/Lukko/OFD.hsc new file mode 100644 --- /dev/null +++ b/src-ofd/Lukko/OFD.hsc @@ -0,0 +1,174 @@ +{-# LANGUAGE CPP #-} +{-# LANGUAGE InterruptibleFFI #-} +{-# LANGUAGE Trustworthy #-} +-- | Linux open file descriptor locking. +-- +-- +-- +-- We prefer this over BSD locking (e.g. flock) since the latter appears to +-- break in some NFS configurations. Note that we intentionally do not try to +-- use ordinary POSIX file locking due to its peculiar semantics under +-- multi-threaded environments. +-- +module Lukko.OFD ( + -- * Types + FileLockingNotSupported(..), + fileLockingSupported, + FileLockingMethod (..), + fileLockingMethod, + LockMode(..), + -- * File descriptors + FD, + fdOpen, + fdClose, + fdLock, + fdTryLock, + fdUnlock, + -- * Handles + hLock, + hTryLock, + hUnlock, + ) where + +#define _GNU_SOURCE +#include +#include + +import Control.Monad (void) +import System.IO (Handle) + +import Data.Function +import Foreign.C.Error +import Foreign.C.Types +import Foreign.Marshal.Utils +import Foreign.Storable +import GHC.IO.Exception +import GHC.Ptr +import System.Posix.Types (COff, CPid) + +import Lukko.Internal.FD +import Lukko.Internal.FillBytes +import Lukko.Internal.Types + +------------------------------------------------------------------------------- +-- Support constants +------------------------------------------------------------------------------- + +-- | A constants specifying whether file locking is supported. +fileLockingSupported :: Bool +fileLockingSupported = True + +-- | A constant specifying this method +fileLockingMethod :: FileLockingMethod +fileLockingMethod = MethodOFD + +------------------------------------------------------------------------------- +-- FD +------------------------------------------------------------------------------- + +-- | Lock using OFD locks. +fdLock :: FD -> LockMode -> IO () +fdLock fd mode = void (lockImpl Nothing fd "fdLock" mode True) + +-- | Try to lock using OFD locks. +fdTryLock :: FD -> LockMode -> IO Bool +fdTryLock fd mode = lockImpl Nothing fd "fdTryLock" mode False + +-- | Unlock using OFD locks. +fdUnlock :: FD -> IO () +fdUnlock = unlockImpl + +------------------------------------------------------------------------------- +-- Handle +------------------------------------------------------------------------------- + +-- | Lock using OFD locks. +hLock :: Handle -> LockMode -> IO () +hLock h mode = do + fd <- handleToFd h + void (lockImpl (Just h) fd "hLock" mode True) + +-- | Try to lock using OFD locks. +hTryLock :: Handle -> LockMode -> IO Bool +hTryLock h mode = do + fd <- handleToFd h + lockImpl (Just h) fd "hTryLock" mode False + +-- | Unlock using OFD locks. +hUnlock :: Handle -> IO () +hUnlock h = do + fd <- handleToFd h + unlockImpl fd + +------------------------------------------------------------------------------- +-- Compat +------------------------------------------------------------------------------- + +-- there is no alignment in old hsc2hs +#let alignmentcompat t = "%lu", (unsigned long)offsetof(struct {char x__; t (y__); }, y__) + +------------------------------------------------------------------------------- +-- implementation +------------------------------------------------------------------------------- + +foreign import ccall interruptible "fcntl" + c_fcntl :: CInt -> CInt -> Ptr FLock -> IO CInt + +data FLock = FLock { l_type :: CShort + , l_whence :: CShort + , l_start :: COff + , l_len :: COff + , l_pid :: CPid + } + +instance Storable FLock where + sizeOf _ = #{size struct flock} + alignment _ = #{alignmentcompat struct flock} + poke ptr x = do + fillBytes ptr 0 (sizeOf x) + #{poke struct flock, l_type} ptr (l_type x) + #{poke struct flock, l_whence} ptr (l_whence x) + #{poke struct flock, l_start} ptr (l_start x) + #{poke struct flock, l_len} ptr (l_len x) + #{poke struct flock, l_pid} ptr (l_pid x) + peek ptr = do + x1 <- #{peek struct flock, l_type} ptr + x2 <- #{peek struct flock, l_whence} ptr + x3 <- #{peek struct flock, l_start} ptr + x4 <- #{peek struct flock, l_len} ptr + x5 <- #{peek struct flock, l_pid} ptr + return (FLock x1 x2 x3 x4 x5) + +lockImpl :: Maybe Handle -> FD -> String -> LockMode -> Bool -> IO Bool +lockImpl mh (FD fd) ctx mode block = do + with flock $ \flock_ptr -> fix $ \retry -> do + ret <- c_fcntl fd mode' flock_ptr + case ret of + 0 -> return True + _ -> getErrno >>= \errno -> case () of + _ | not block && errno == eWOULDBLOCK -> return False + | errno == eINTR -> retry + | otherwise -> ioException $ errnoToIOError ctx errno mh Nothing + where + flock = FLock { l_type = case mode of + SharedLock -> #{const F_RDLCK} + ExclusiveLock -> #{const F_WRLCK} + , l_whence = #{const SEEK_SET} + , l_start = 0 + , l_len = 0 + , l_pid = 0 + } + mode' + | block = #{const F_OFD_SETLKW} + | otherwise = #{const F_OFD_SETLK} + +unlockImpl :: FD -> IO () +unlockImpl (FD fd) = do + let flock = FLock { l_type = #{const F_UNLCK} + , l_whence = #{const SEEK_SET} + , l_start = 0 + , l_len = 0 + , l_pid = 0 + } + throwErrnoIfMinus1_ "hUnlock" + $ with flock $ c_fcntl fd #{const F_OFD_SETLK} diff --git a/src-unix/Lukko/Internal/FD.hsc b/src-unix/Lukko/Internal/FD.hsc new file mode 100644 --- /dev/null +++ b/src-unix/Lukko/Internal/FD.hsc @@ -0,0 +1,63 @@ +{-# LANGUAGE CPP #-} +{-# LANGUAGE InterruptibleFFI #-} +{-# LANGUAGE Trustworthy #-} +module Lukko.Internal.FD ( + FD (..), + fdOpen, + fdClose, + handleToFd, + ) where + +#include +#include + +import Data.Bits ((.|.)) +import Foreign.C.Error (throwErrnoIfMinus1Retry) +import Foreign.C.Types +import Foreign.C.String (CString, withCString) +import System.IO (Handle) +import System.Posix.Types (CMode (..)) + +import qualified GHC.IO.FD as GHC (FD (..)) + +import Lukko.Internal.HandleToFD (ghcHandleToFd) + +-- | Opaque /file descriptor/ +-- +-- This is a wrapper over 'CInt' +newtype FD = FD CInt + +foreign import ccall interruptible "open" + c_open :: CString -> CInt -> CMode -> IO CInt + +foreign import ccall interruptible "close" + c_close :: CInt -> IO CInt + +-- | Open file to be used for locking. +-- +-- @ +-- open(path, O_RDWR | O_CREAT); +-- @ +fdOpen :: FilePath -> IO FD +fdOpen fp = withCString fp $ \cfp -> do + fd <- throwErrnoIfMinus1Retry "open" $ c_open cfp flags mode + return (FD fd) + where + flags = #{const O_RDWR} .|. #{const O_CREAT} + mode = CMode 0o666 + +-- | Close lock file. +-- +-- @ +-- close(fd); +-- @ +fdClose :: FD -> IO () +fdClose (FD fd) = do + ret <- throwErrnoIfMinus1Retry "close" $ c_close fd + return () + +-- | Convert GHC 'Handle' to lukko 'FD'. +handleToFd :: Handle -> IO FD +handleToFd h = do + GHC.FD {GHC.fdFD = fd} <- ghcHandleToFd h + return (FD fd) diff --git a/src-windows/Lukko/Internal/FD.hsc b/src-windows/Lukko/Internal/FD.hsc new file mode 100644 --- /dev/null +++ b/src-windows/Lukko/Internal/FD.hsc @@ -0,0 +1,86 @@ +{-# LANGUAGE CPP #-} +{-# LANGUAGE InterruptibleFFI #-} +{-# LANGUAGE Trustworthy #-} +module Lukko.Internal.FD ( + FD (..), + fdOpen, + fdClose, + handleToFd, + ) where + +import System.IO (Handle) +import GHC.Windows (iNVALID_HANDLE_VALUE, HANDLE, LPWSTR, BOOL, getLastError, failWith) +import Foreign.C.Types (CInt (..)) +import Foreign.C.Error (throwErrnoIf) +import Foreign.C.String (withCWString) +import Foreign.Ptr (Ptr) + +import qualified GHC.IO.FD as GHC (FD (..)) + +import Lukko.Internal.HandleToFD (ghcHandleToFd) + +-- | Opaque /file descriptor/ +-- +-- This is a wrapper over 'HANDLE' +newtype FD = FD HANDLE + +-- | Open file to be used for locking +-- +-- @ +-- createFileW(path, +-- GENERIC_WRITE | GENERIC_READ, +-- FILE_SHARE_READ | FILE_SHARE_WRITE, +-- securityAttributes, // bInheritHandle = TRUE +-- OPEN_ALWAYS, +-- FILE_ATTRIBUTE_NORMAL, +-- NULL); +-- @ +fdOpen :: FilePath -> IO FD +fdOpen fp = withCWString fp $ \cfp -> do + fw <- c_fdOpen cfp + if fw /= iNVALID_HANDLE_VALUE + then return (FD fw) + else getLastError >>= failWith "fdOpen" + +-- | Close lock file. +-- +-- @ +-- CloseHandle(h); +-- @ +fdClose :: FD -> IO () +fdClose (FD fw) = do + r <- c_CloseHandle fw + if r + then return () + else getLastError >>= failWith "fdClose" + +-- | Convert GHC 'Handle' to lukko 'FD'. +handleToFd :: Handle -> IO FD +handleToFd h = do + GHC.FD {GHC.fdFD = fd} <- ghcHandleToFd h + wh <- throwErrnoIf (== iNVALID_HANDLE_VALUE) "handleToFd" $ c_get_osfhandle fd + return (FD wh) + +-- https://msdn.microsoft.com/en-us/library/aa297958.aspx +foreign import ccall unsafe "_get_osfhandle" + c_get_osfhandle :: CInt -> IO HANDLE + +-- Opening file is complicated +foreign import ccall interruptible "fdOpen" + c_fdOpen :: LPWSTR -> IO HANDLE + +#if defined(i386_HOST_ARCH) + +-- https://docs.microsoft.com/en-gb/windows/win32/api/handleapi/nf-handleapi-closehandle +foreign import stdcall interruptible "CloseHandle" + c_CloseHandle :: HANDLE -> IO BOOL + +#elif defined(x86_64_HOST_ARCH) + +-- https://docs.microsoft.com/en-gb/windows/win32/api/handleapi/nf-handleapi-closehandle +foreign import ccall interruptible "CloseHandle" + c_CloseHandle :: HANDLE -> IO BOOL + +#else +#error Unknown mingw32 arch +#endif diff --git a/src-windows/Lukko/Windows.hsc b/src-windows/Lukko/Windows.hsc new file mode 100644 --- /dev/null +++ b/src-windows/Lukko/Windows.hsc @@ -0,0 +1,159 @@ +{-# LANGUAGE CPP #-} +{-# LANGUAGE InterruptibleFFI #-} +{-# LANGUAGE Trustworthy #-} +-- | File locking for Windows. +module Lukko.Windows ( + -- * Types + FileLockingNotSupported(..), + fileLockingSupported, + FileLockingMethod (..), + fileLockingMethod, + LockMode(..), + -- * File descriptors + FD, + fdOpen, + fdClose, + fdLock, + fdTryLock, + fdUnlock, + -- * Handles + hLock, + hTryLock, + hUnlock, + ) where + +#include + +import Control.Monad (void) +import System.IO (Handle) + +import Data.Bits +import Data.Function +import Foreign.C.Error +import Foreign.C.Types +import Foreign.Marshal.Alloc +import Foreign.Marshal.Utils +import Foreign.Ptr (Ptr) +import GHC.Windows + +import Lukko.Internal.FD +import Lukko.Internal.FillBytes +import Lukko.Internal.Types + +#if defined(i386_HOST_ARCH) +#define WINDOWS_CCONV stdcall +#elif defined(x86_64_HOST_ARCH) +#define WINDOWS_CCONV ccall +#else +#error Unknown mingw32 arch +#endif + +------------------------------------------------------------------------------- +-- Support constants +------------------------------------------------------------------------------- + +-- | A constants specifying whether file locking is supported. +fileLockingSupported :: Bool +fileLockingSupported = True + +-- | A constant specifying this method +fileLockingMethod :: FileLockingMethod +fileLockingMethod = MethodWindows + +------------------------------------------------------------------------------- +-- FD +------------------------------------------------------------------------------- + +-- | Lock using OFD locks. +fdLock :: FD -> LockMode -> IO () +fdLock fd mode = void (lockImpl Nothing fd "fdLock" mode True) + +-- | Try to lock using OFD locks. +fdTryLock :: FD -> LockMode -> IO Bool +fdTryLock fd mode = lockImpl Nothing fd "fdTryLock" mode False + +-- | Unlock using OFD locks. +fdUnlock :: FD -> IO () +fdUnlock = unlockImpl + +------------------------------------------------------------------------------- +-- Handle +------------------------------------------------------------------------------- + +-- | Lock using OFD locks. +hLock :: Handle -> LockMode -> IO () +hLock h mode = do + fd <- handleToFd h + void (lockImpl (Just h) fd "hLock" mode True) + +-- | Try to lock using OFD locks. +hTryLock :: Handle -> LockMode -> IO Bool +hTryLock h mode = do + fd <- handleToFd h + lockImpl (Just h) fd "hTryLock" mode False + +-- | Unlock using OFD locks. +hUnlock :: Handle -> IO () +hUnlock h = do + fd <- handleToFd h + unlockImpl fd + +------------------------------------------------------------------------------- +-- implementation +------------------------------------------------------------------------------- + +lockImpl :: Maybe Handle -> FD -> String -> LockMode -> Bool -> IO Bool +lockImpl _ (FD wh) ctx mode block = do + allocaBytes sizeof_OVERLAPPED $ \ovrlpd -> do + fillBytes ovrlpd 0 sizeof_OVERLAPPED + let flags = cmode .|. (if block then 0 else #{const LOCKFILE_FAIL_IMMEDIATELY}) + -- We want to lock the whole file without looking up its size to be + -- consistent with what flock does. According to documentation of LockFileEx + -- "locking a region that goes beyond the current end-of-file position is + -- not an error", hence we pass maximum value as the number of bytes to + -- lock. + fix $ \retry -> c_LockFileEx wh flags 0 0xffffffff 0xffffffff ovrlpd >>= \res -> case res of + True -> return True + False -> getLastError >>= \err -> case () of + _ | not block && err == #{const ERROR_LOCK_VIOLATION} -> return False + | err == #{const ERROR_OPERATION_ABORTED} -> retry + | otherwise -> failWith ctx err + where + sizeof_OVERLAPPED = #{size OVERLAPPED} + + cmode = case mode of + SharedLock -> 0 + ExclusiveLock -> #{const LOCKFILE_EXCLUSIVE_LOCK} + +unlockImpl :: FD -> IO () +unlockImpl (FD wh) = do + allocaBytes sizeof_OVERLAPPED $ \ovrlpd -> do + fillBytes ovrlpd 0 sizeof_OVERLAPPED + c_UnlockFileEx wh 0 0xffffffff 0xffffffff ovrlpd >>= \res -> case res of + True -> return () + False -> getLastError >>= failWith "fdUnlock" + where + sizeof_OVERLAPPED = #{size OVERLAPPED} +#if defined(i386_HOST_ARCH) + +-- https://docs.microsoft.com/en-gb/windows/win32/api/fileapi/nf-fileapi-lockfileex +foreign import stdcall interruptible "LockFileEx" + c_LockFileEx :: HANDLE -> DWORD -> DWORD -> DWORD -> DWORD -> Ptr () -> IO BOOL + +-- https://docs.microsoft.com/en-gb/windows/win32/api/fileapi/nf-fileapi-unlockfileex +foreign import stdcall interruptible "UnlockFileEx" + c_UnlockFileEx :: HANDLE -> DWORD -> DWORD -> DWORD -> Ptr () -> IO BOOL + +#elif defined(x86_64_HOST_ARCH) + +-- https://docs.microsoft.com/en-gb/windows/win32/api/fileapi/nf-fileapi-lockfileex +foreign import ccall interruptible "LockFileEx" + c_LockFileEx :: HANDLE -> DWORD -> DWORD -> DWORD -> DWORD -> Ptr () -> IO BOOL + +-- https://docs.microsoft.com/en-gb/windows/win32/api/fileapi/nf-fileapi-unlockfileex +foreign import ccall interruptible "UnlockFileEx" + c_UnlockFileEx :: HANDLE -> DWORD -> DWORD -> DWORD -> Ptr () -> IO BOOL + +#else +#error Unknown mingw32 arch +#endif diff --git a/src/Lukko.hs b/src/Lukko.hs new file mode 100644 --- /dev/null +++ b/src/Lukko.hs @@ -0,0 +1,145 @@ +{-# LANGUAGE CPP #-} +{-# LANGUAGE Trustworthy #-} +-- | Open 'Handle' based locking +module Lukko ( + FileLockingNotSupported(..), + Impl.fileLockingSupported, + FileLockingMethod (..), + Impl.fileLockingMethod, + LockMode(..), + -- * File descriptors + FD, + fdOpen, + fdClose, + fdLock, + fdTryLock, + fdUnlock, + -- * Handles + handleToFd, + hLock, + hTryLock, + hUnlock, + ) where + +{- Parts of these software is derived from GHC sources + distributed under BSD-3-Clause license: + +The Glasgow Haskell Compiler License + +Copyright 2004, The University Court of the University of Glasgow. +All rights reserved. + +Redistribution and use in source and binary forms, with or without +modification, are permitted provided that the following conditions are met: + +- Redistributions of source code must retain the above copyright notice, +this list of conditions and the following disclaimer. + +- Redistributions in binary form must reproduce the above copyright notice, +this list of conditions and the following disclaimer in the documentation +and/or other materials provided with the distribution. + +- Neither name of the University nor the names of its contributors may be +used to endorse or promote products derived from this software without +specific prior written permission. + +THIS SOFTWARE IS PROVIDED BY THE UNIVERSITY COURT OF THE UNIVERSITY OF +GLASGOW AND THE CONTRIBUTORS "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, +INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND +FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE +UNIVERSITY COURT OF THE UNIVERSITY OF GLASGOW OR THE CONTRIBUTORS BE LIABLE +FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL +DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR +SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER +CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT +LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY +OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH +DAMAGE. + +-} + +import Control.Monad (void) +import System.IO (Handle) + +import Lukko.Internal.Types + +import qualified Lukko.Internal.FD as Impl + +#if defined(USE_OFD_LOCKING) +import qualified Lukko.OFD as Impl +#elif defined(USE_FLOCK) +import qualified Lukko.FLock as Impl +#elif defined(USE_WINDOWS_LOCK) +import qualified Lukko.Windows as Impl +#else +import qualified Lukko.NoOp as Impl +#endif + +------------------------------------------------------------------------------- +-- Handles +------------------------------------------------------------------------------- + +-- | If a 'Handle' references a file descriptor, attempt to lock contents of the +-- underlying file in appropriate mode. If the file is already locked in +-- incompatible mode, this function blocks until the lock is established. The +-- lock is automatically released upon closing a 'Handle'. +-- +-- Things to be aware of: +-- +-- 1) This function may block inside a C call. If it does, in order to be able +-- to interrupt it with asynchronous exceptions and/or for other threads to +-- continue working, you MUST use threaded version of the runtime system. +-- +-- 2) The implementation uses 'LockFileEx' on Windows, +-- /open file descriptor/ locks on Linux, and 'flock' otherwise, +-- hence all of their caveats also apply here. +-- +-- 3) On non-Windows plaftorms that don't support 'flock' (e.g. Solaris) this +-- function throws 'FileLockingNotImplemented'. We deliberately choose to not +-- provide @fcntl@ based locking instead because of its broken semantics. +-- +hLock :: Handle -> LockMode -> IO () +hLock = Impl.hLock + +-- | Non-blocking version of 'hLock'. +hTryLock :: Handle -> LockMode -> IO Bool +hTryLock = Impl.hTryLock + +-- | Release a lock taken with 'hLock' or 'hTryLock'. +hUnlock :: Handle -> IO () +hUnlock = Impl.hUnlock + +------------------------------------------------------------------------------- +-- File descriptors +------------------------------------------------------------------------------- + +-- | Opaque /file descriptor/ +-- +-- An @int@ / 'CInt' on unix systems, +-- and 'HANDLE' on windows. +type FD = Impl.FD + +-- | Open file to be used for locking. +fdOpen :: FilePath -> IO FD +fdOpen = Impl.fdOpen + +-- | Close lock file. +fdClose :: FD -> IO () +fdClose = Impl.fdClose + +-- | Convert GHC 'Handle' to lukko 'FD'. +handleToFd :: Handle -> IO FD +handleToFd = Impl.handleToFd + +-- | Like 'hLock', but work on "raw" file descriptor, +-- as handled by 'fdOpen' and 'fdClose'. +fdLock :: Impl.FD -> LockMode -> IO () +fdLock = Impl.fdLock + +-- | Non-blocking version of 'fdLock'. +fdTryLock :: Impl.FD -> LockMode -> IO Bool +fdTryLock = Impl.fdTryLock + +-- | Release a lock taken with 'fdLock' or 'fdTryLock'. +fdUnlock :: Impl.FD -> IO () +fdUnlock = Impl.fdUnlock diff --git a/src/Lukko/Internal/FillBytes.hs b/src/Lukko/Internal/FillBytes.hs new file mode 100644 --- /dev/null +++ b/src/Lukko/Internal/FillBytes.hs @@ -0,0 +1,21 @@ +{-# LANGUAGE CPP #-} +{-# LANGUAGE InterruptibleFFI #-} +{-# LANGUAGE Trustworthy #-} +module Lukko.Internal.FillBytes (fillBytes) where + +#if MIN_VERSION_base(4,8,0) +import Foreign.Marshal.Utils (fillBytes) +#else +import Data.Word (Word8) +import Foreign.C.Types (CInt (..), CSize (..)) +import Foreign.Ptr (Ptr (..)) +#endif + +#if !MIN_VERSION_base(4,8,0) +fillBytes :: Ptr a -> Word8 -> Int -> IO () +fillBytes dest char size = do + _ <- memset dest (fromIntegral char) (fromIntegral size) + return () + +foreign import ccall unsafe "string.h" memset :: Ptr a -> CInt -> CSize -> IO (Ptr a) +#endif diff --git a/src/Lukko/Internal/HandleToFD.hs b/src/Lukko/Internal/HandleToFD.hs new file mode 100644 --- /dev/null +++ b/src/Lukko/Internal/HandleToFD.hs @@ -0,0 +1,32 @@ +{-# LANGUAGE CPP #-} +{-# LANGUAGE Trustworthy #-} +module Lukko.Internal.HandleToFD (ghcHandleToFd) where + +import qualified GHC.IO.FD as GHC (FD (..)) +import System.IO (Handle) + +#if MIN_VERSION_base(4,10,0) +import qualified GHC.IO.Handle.FD as GHC (handleToFd) +#else +import Control.Concurrent.MVar (readMVar) +import Data.Typeable (cast) +import GHC.IO.Exception +import GHC.IO.Handle.Internals +import GHC.IO.Handle.Types +#endif + +ghcHandleToFd :: Handle -> IO GHC.FD +#if MIN_VERSION_base(4,10,0) +ghcHandleToFd = GHC.handleToFd +#else +ghcHandleToFd h = case h of + FileHandle _ mv -> do + Handle__{haDevice = dev} <- readMVar mv + case cast dev of + Just fd -> return fd + Nothing -> throwErr "not a file descriptor" + DuplexHandle{} -> throwErr "not a file handle" + where + throwErr msg = ioException $ IOError (Just h) + InappropriateType "handleToFd" msg Nothing Nothing +#endif diff --git a/src/Lukko/Internal/Types.hs b/src/Lukko/Internal/Types.hs new file mode 100644 --- /dev/null +++ b/src/Lukko/Internal/Types.hs @@ -0,0 +1,25 @@ +{-# LANGUAGE DeriveDataTypeable #-} +{-# LANGUAGE Safe #-} +module Lukko.Internal.Types where + +import Control.Exception (Exception) +import Data.Typeable (Typeable) + +-- | Exception thrown by 'hLock' on non-Windows platforms that don't support +-- @flock@. +data FileLockingNotSupported = FileLockingNotSupported + deriving (Typeable, Show) + +instance Exception FileLockingNotSupported + +-- | Indicates a mode in which a file should be locked. +data LockMode = SharedLock | ExclusiveLock + deriving (Typeable) + +-- | Potentially availble lock methods. +data FileLockingMethod + = MethodOFD -- ^ open file descriptor locking + | MethodFLock -- ^ BSD @flock@ + | MethodWindows -- ^ Windows locking + | MethodNoOp -- ^ No-Op (throws 'FileLockingNotSupported') + deriving (Typeable, Eq, Ord, Enum, Bounded, Show) diff --git a/src/Lukko/NoOp.hs b/src/Lukko/NoOp.hs new file mode 100644 --- /dev/null +++ b/src/Lukko/NoOp.hs @@ -0,0 +1,62 @@ +{-# LANGUAGE DataKinds #-} +{-# LANGUAGE Safe #-} +-- | Non-operating locks. +-- +-- All functions throw 'FileLockingNotImplemented'. +module Lukko.NoOp ( + -- * Types + FileLockingNotSupported(..), + fileLockingSupported, + FileLockingMethod (..), + fileLockingMethod, + LockMode(..), + -- * File descriptors + FD, + fdOpen, + fdClose, + fdLock, + fdTryLock, + fdUnlock, + -- * Handles + hLock, + hTryLock, + hUnlock, + ) where + +import Control.Exception (throwIO) +import System.IO (Handle) + +import Lukko.Internal.FD +import Lukko.Internal.Types + +-- | A constants specifying whether file locking is supported. +fileLockingSupported :: Bool +fileLockingSupported = False + +-- | A constant specifying this method +fileLockingMethod :: FileLockingMethod +fileLockingMethod = MethodNoOp + +-- | No-op implementation. +hLock :: Handle -> LockMode -> IO () +hLock _ _ = throwIO FileLockingNotSupported + +-- | No-op implementation +hTryLock :: Handle -> LockMode -> IO Bool +hTryLock _ _ = throwIO FileLockingNotSupported + +-- | No-op implementation. +hUnlock :: Handle -> IO () +hUnlock _ = throwIO FileLockingNotSupported + +-- | No-op implementation. +fdLock :: FD -> LockMode -> IO () +fdLock _ _ = throwIO FileLockingNotSupported + +-- | No-op implementation +fdTryLock :: FD -> LockMode -> IO Bool +fdTryLock _ _ = throwIO FileLockingNotSupported + +-- | No-op implementation. +fdUnlock :: FD -> IO () +fdUnlock _ = throwIO FileLockingNotSupported diff --git a/test/TestProcess.hs b/test/TestProcess.hs new file mode 100644 --- /dev/null +++ b/test/TestProcess.hs @@ -0,0 +1,75 @@ +{-# LANGUAGE CPP #-} +{-# LANGUAGE OverloadedStrings #-} +{-# LANGUAGE RankNTypes #-} +module Main (main) where + +import Control.Concurrent (threadDelay) +import Control.Exception (bracket) +import System.Environment (getArgs) +import System.IO (Handle, IOMode (ReadWriteMode), hClose, openFile) + +import qualified Data.ByteString as BS +import qualified Data.ByteString.Char8 as BS8 + +import Lukko + +#ifdef HAS_OFD_LOCKING +import qualified Lukko.OFD as OFD +#endif + +#ifdef HAS_FLOCK +import qualified Lukko.FLock as FLock +#endif + +main :: IO () +main = withArgs $ \withLock -> do + putStrLn "starting..." + withLock $ do + contents <- BS.readFile "test-actual" + threadDelay 10000 -- 10 ms + BS.writeFile "test-actual" $ BS.append contents $ BS8.pack "another line\n" + +withArgs + :: ((forall r. IO r -> IO r) -> IO ()) + -> IO () +withArgs k = do + args <- getArgs + case args of + ["default"] -> k (genWithLock hLock hUnlock "test-lock") +#ifdef HAS_OFD_LOCKING + ["ofd"] -> k (genWithLock OFD.hLock OFD.hUnlock "test-lock") +#endif +#ifdef HAS_FLOCK + ["flock"] -> k (genWithLock FLock.hLock FLock.hUnlock "test-lock") +#endif + ["noop"] -> k (genWithLock noOpLock noOpUnlock "test-lock") + _ -> putStrLn "Unknown paramters. Doing nothing." + +------------------------------------------------------------------------------- +-- copy pasted +------------------------------------------------------------------------------- + +noOpLock :: Handle -> LockMode -> IO () +noOpLock _ _ = return () + +noOpUnlock :: Handle -> IO () +noOpUnlock _ = return () + +genWithLock + :: (Handle -> LockMode -> IO ()) + -> (Handle -> IO ()) + -> FilePath + -> IO a + -> IO a +genWithLock implLock implUnlock fp action = + bracket takeLock releaseLock (const action) + where + takeLock = do + h <- openFile fp ReadWriteMode + implLock h ExclusiveLock + return h + + releaseLock :: Handle -> IO () + releaseLock h = do + implUnlock h + hClose h diff --git a/test/Tests.hs b/test/Tests.hs new file mode 100644 --- /dev/null +++ b/test/Tests.hs @@ -0,0 +1,77 @@ +{-# LANGUAGE CPP #-} +module Main (main) where + +import Control.Concurrent (threadDelay) +import Control.Concurrent.Async (forConcurrently_) +import Control.Exception (bracket) +import Data.IORef +import System.FilePath (()) +import System.IO + (Handle, IOMode (ReadWriteMode), hClose, openFile) +import System.IO.Temp (withSystemTempDirectory) +import Test.Tasty (TestTree, defaultMain, testGroup) +import Test.Tasty.HUnit (testCase, (@=?)) + +import Lukko + +#ifdef HAS_OFD_LOCKING +import qualified Lukko.OFD as OFD +#endif + +#ifdef HAS_FLOCK +import qualified Lukko.FLock as FLock +#endif + +main :: IO () +main = defaultMain $ testGroup "lukko" $ + [ testGroup "Lukko default" $ testSuite fdLock fdUnlock + | fileLockingSupported + ] +#ifdef HAS_OFD_LOCKING + ++ [ testGroup "Lukko.OFD" $ testSuite OFD.fdLock OFD.fdUnlock ] +#endif +#ifdef HAS_FLOCK + ++ [ testGroup "Lukko.FLock" $ testSuite FLock.fdLock FLock.fdUnlock ] +#endif + +testSuite + :: (FD -> LockMode -> IO ()) + -> (FD -> IO ()) + -> [TestTree] +testSuite implLock implUnlock = + [ testCase "concurrent threads" $ do + let n = 10 :: Int + ref <- newIORef 0 + + withSystemTempDirectory "handle-lock-tests" $ \tmpDir -> do + -- print tmpDir + forConcurrently_ [1 :: Int .. n] $ \_ -> + withLock (tmpDir "lock") $ do + val <- readIORef ref + threadDelay 10000 -- 10ms + writeIORef ref (succ val) + + val <- readIORef ref + val @=? n + ] + where + withLock = genWithLock implLock implUnlock + +genWithLock + :: (FD -> LockMode -> IO ()) + -> (FD -> IO ()) + -> FilePath + -> IO a + -> IO a +genWithLock implLock implUnlock fp action = + bracket takeLock releaseLock (const action) + where + takeLock = do + fd <- fdOpen fp + implLock fd ExclusiveLock + return fd + + releaseLock :: FD -> IO () + releaseLock fd = do + implUnlock fd + fdClose fd