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