dist-install/build/System/Posix/SharedMem.hs

    {-# LINE 1 "libraries/unix/System/Posix/SharedMem.hsc" #-}

    {-# LINE 2 "libraries/unix/System/Posix/SharedMem.hsc" #-}
    {-# LANGUAGE Safe #-}

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    -----------------------------------------------------------------------------
    -- |
    -- Module      :  System.Posix.SharedMem
    -- Copyright   :  (c) Daniel Franke 2007
    -- License     :  BSD-style (see the file libraries/base/LICENSE)
    --
    -- Maintainer  :  libraries@haskell.org
    -- Stability   :  experimental
    -- Portability :  non-portable (requires POSIX)
    --
    -- POSIX shared memory support.
    --
    -----------------------------------------------------------------------------

    module System.Posix.SharedMem
        (ShmOpenFlags(..), shmOpen, shmUnlink)
        where

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    import System.Posix.Types

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    import Foreign.C

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    import Data.Bits

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    data ShmOpenFlags = ShmOpenFlags
        { shmReadWrite :: Bool,
          -- ^ If true, open the shm object read-write rather than read-only.
          shmCreate :: Bool,
          -- ^ If true, create the shm object if it does not exist.
          shmExclusive :: Bool,
          -- ^ If true, throw an exception if the shm object already exists.
          shmTrunc :: Bool
          -- ^ If true, wipe the contents of the shm object after opening it.
        }

    -- | Open a shared memory object with the given name, flags, and mode.
    shmOpen :: String -> ShmOpenFlags -> FileMode -> IO Fd

    {-# LINE 52 "libraries/unix/System/Posix/SharedMem.hsc" #-}
    shmOpen name flags mode =
        do cflags0 <- return 0
           cflags1 <- return $ cflags0 .|. (if shmReadWrite flags
                                            then 2
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                                            else 0)
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           cflags2 <- return $ cflags1 .|. (if shmCreate flags then 64
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                                            else 0)
           cflags3 <- return $ cflags2 .|. (if shmExclusive flags
                                            then 128
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                                            else 0)
           cflags4 <- return $ cflags3 .|. (if shmTrunc flags then 512
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                                            else 0)
           withCAString name (shmOpen' cflags4)
        where shmOpen' cflags cname =
                  do fd <- throwErrnoIfMinus1 "shmOpen" $
                           shm_open cname cflags mode
                     return $ Fd fd

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    -- | Delete the shared memory object with the given name.
    shmUnlink :: String -> IO ()

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    shmUnlink name = withCAString name shmUnlink'
        where shmUnlink' cname =
                  throwErrnoIfMinus1_ "shmUnlink" $ shm_unlink cname

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    foreign import ccall unsafe "shm_open"
            shm_open :: CString -> CInt -> CMode -> IO CInt

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    foreign import ccall unsafe "shm_unlink"
            shm_unlink :: CString -> IO CInt

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