module GHC.IO.Handle.Lock.Flock where
import Data.Bits
import Data.Function
import Foreign.C.Error
import Foreign.C.Types
import GHC.Base
import GHC.IO.Exception
import GHC.IO.FD
import GHC.IO.Handle.FD
import GHC.IO.Handle.Lock.Common
import GHC.IO.Handle.Types (Handle)
lockImpl :: Handle -> String -> LockMode -> Bool -> IO Bool
lockImpl h ctx mode block = do
FD{fdFD = fd} <- handleToFd h
let flags = cmode .|. (if block then 0 else 4)
fix $ \retry -> c_flock fd flags >>= \case
0 -> return True
_ -> getErrno >>= \errno -> if
| not block
, errno == eAGAIN || errno == eACCES -> return False
| errno == eINTR -> retry
| otherwise -> ioException $ errnoToIOError ctx errno (Just h) Nothing
where
cmode = case mode of
SharedLock -> 1
ExclusiveLock -> 2
unlockImpl :: Handle -> IO ()
unlockImpl h = do
FD{fdFD = fd} <- handleToFd h
throwErrnoIfMinus1_ "flock" $ c_flock fd 8
foreign import ccall interruptible "flock"
c_flock :: CInt -> CInt -> IO CInt