dist-install/build/System/Posix/DynamicLinker/ByteString.hs

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

    {-# LINE 2 "libraries/unix/System/Posix/DynamicLinker/ByteString.hsc" #-}
    {-# LANGUAGE Trustworthy #-}

    {-# LINE 4 "libraries/unix/System/Posix/DynamicLinker/ByteString.hsc" #-}
    -----------------------------------------------------------------------------
    -- |
    -- Module      :  System.Posix.DynamicLinker.ByteString
    -- Copyright   :  (c) Volker Stolz <vs@foldr.org> 2003
    -- License     :  BSD-style (see the file libraries/base/LICENSE)
    --
    -- Maintainer  :  vs@foldr.org
    -- Stability   :  provisional
    -- Portability :  non-portable (requires POSIX)
    --
    -- Dynamic linker support through dlopen()
    -----------------------------------------------------------------------------

    module System.Posix.DynamicLinker.ByteString (

        module System.Posix.DynamicLinker.Prim,
        dlopen,
        dlsym,
        dlerror,
        dlclose,
        withDL, withDL_,
        undl,
        )

    --  Usage:
    --  ******
    --
    --  Let's assume you want to open a local shared library \'foo\' (.\/libfoo.so)
    --  offering a function
    --    @char \* mogrify (char\*,int)@
    --  and invoke @str = mogrify("test",1)@:
    --
    --
    --  type Fun = CString -> Int -> IO CString
    --  foreign import dynamic unsafe fun__ :: FunPtr Fun -> Fun
    --
    --  withDL "libfoo.so" [RTLD_NOW] \$ \\ mod -> do
    --     funptr <- dlsym mod "mogrify"
    --     let fun = fun__ funptr
    --     withCString "test" \$ \\ str -> do
    --       strptr <- fun str 1
    --       strstr <- peekCString strptr
    --       ...
    --

    where

    import System.Posix.DynamicLinker.Common
    import System.Posix.DynamicLinker.Prim

    {-# LINE 55 "libraries/unix/System/Posix/DynamicLinker/ByteString.hsc" #-}

    import Control.Exception        ( bracket )
    import Control.Monad	( liftM )
    import Foreign
    import System.Posix.ByteString.FilePath

    dlopen :: RawFilePath -> [RTLDFlags] -> IO DL
    dlopen path flags = do
      withFilePath path $ \ p -> do
        liftM DLHandle $ throwDLErrorIf "dlopen" (== nullPtr) $ c_dlopen p (packRTLDFlags flags)

    withDL :: RawFilePath -> [RTLDFlags] -> (DL -> IO a) -> IO a
    withDL file flags f = bracket (dlopen file flags) (dlclose) f

    withDL_ :: RawFilePath -> [RTLDFlags] -> (DL -> IO a) -> IO ()
    withDL_ file flags f = withDL file flags f >> return ()