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{-# LANGUAGE CApiFFI #-}
#if __GLASGOW_HASKELL__ >= 709
{-# LANGUAGE Safe #-}
#else
{-# LANGUAGE Trustworthy #-}
#endif
-----------------------------------------------------------------------------
-- |
-- Module : System.Posix.Fcntl
-- Copyright : (c) The University of Glasgow 2014
-- License : BSD-style (see the file LICENSE)
--
-- Maintainer : libraries@haskell.org
-- Stability : provisional
-- Portability : non-portable (requires POSIX)
--
-- POSIX file control support
--
-- /Since: 2.7.1.0/
-----------------------------------------------------------------------------
#include "HsUnix.h"
module System.Posix.Fcntl (
-- * File allocation
Advice(..), fileAdvise,
fileAllocate,
) where
#if HAVE_POSIX_FALLOCATE || HAVE_POSIX_FADVISE
import Foreign.C
#endif
import System.Posix.Types
#if !HAVE_POSIX_FALLOCATE
import System.IO.Error ( ioeSetLocation )
import GHC.IO.Exception ( unsupportedOperation )
#endif
-- -----------------------------------------------------------------------------
-- File control
-- | Advice parameter for 'fileAdvise' operation.
--
-- For more details, see documentation of @posix_fadvise(2)@.
--
-- /Since: 2.7.1.0/
data Advice
= AdviceNormal
| AdviceRandom
| AdviceSequential
| AdviceWillNeed
| AdviceDontNeed
| AdviceNoReuse
deriving Eq
-- | Performs @posix_fadvise(2)@ operation on file-descriptor.
--
-- If platform does not provide @posix_fadvise(2)@ 'fileAdvise'
-- becomes a no-op.
--
-- (use @#if HAVE_POSIX_FADVISE@ CPP guard to detect availability)
--
-- /Since: 2.7.1.0/
fileAdvise :: Fd -> FileOffset -> FileOffset -> Advice -> IO ()
#if HAVE_POSIX_FADVISE
fileAdvise fd off len adv = do
throwErrnoIfMinus1_ "fileAdvise" (c_posix_fadvise (fromIntegral fd) (fromIntegral off) (fromIntegral len) (packAdvice adv))
foreign import capi safe "fcntl.h posix_fadvise"
c_posix_fadvise :: CInt -> COff -> COff -> CInt -> IO CInt
packAdvice :: Advice -> CInt
packAdvice AdviceNormal = (#const POSIX_FADV_NORMAL)
packAdvice AdviceRandom = (#const POSIX_FADV_RANDOM)
packAdvice AdviceSequential = (#const POSIX_FADV_SEQUENTIAL)
packAdvice AdviceWillNeed = (#const POSIX_FADV_WILLNEED)
packAdvice AdviceDontNeed = (#const POSIX_FADV_DONTNEED)
packAdvice AdviceNoReuse = (#const POSIX_FADV_NOREUSE)
#else
fileAdvise _ _ _ _ = return ()
#endif
-- | Performs @posix_fallocate(2)@ operation on file-descriptor.
--
-- Throws 'IOError' (\"unsupported operation\") if platform does not
-- provide @posix_fallocate(2)@.
--
-- (use @#if HAVE_POSIX_FALLOCATE@ CPP guard to detect availability).
--
-- /Since: 2.7.1.0/
fileAllocate :: Fd -> FileOffset -> FileOffset -> IO ()
#if HAVE_POSIX_FALLOCATE
fileAllocate fd off len = do
throwErrnoIfMinus1_ "fileAllocate" (c_posix_fallocate (fromIntegral fd) (fromIntegral off) (fromIntegral len))
foreign import capi safe "fcntl.h posix_fallocate"
c_posix_fallocate :: CInt -> COff -> COff -> IO CInt
#else
{-# WARNING fileAllocate
"operation will throw 'IOError' \"unsupported operation\" (CPP guard: @#if HAVE_POSIX_FALLOCATE@)" #-}
fileAllocate _ _ _ = ioError (ioeSetLocation unsupportedOperation
"fileAllocate")
#endif
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