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

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

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

    {-# LINE 4 "libraries/unix/System/Posix/DynamicLinker/Module.hsc" #-}
    -----------------------------------------------------------------------------
    -- |
    -- Module      :  System.Posix.DynamicLinker.Module
    -- 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)
    --
    -- DLOpen support, old API
    --  Derived from GModule.chs by M.Weber & M.Chakravarty which is part of c2hs
    --  I left the API more or less the same, mostly the flags are different.
    --
    -----------------------------------------------------------------------------

    module System.Posix.DynamicLinker.Module (

    --  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
    --
    --  withModule (Just ".") ("libfoo.so") [RTLD_NOW] $ \ mod -> do
    --     funptr <- moduleSymbol mod "mogrify"
    --     let fun = fun__ funptr
    --     withCString "test" $ \ str -> do
    --       strptr <- fun str 1
    --       strstr <- peekCString strptr
    --       ...

          Module
        , moduleOpen             -- :: String -> ModuleFlags -> IO Module
        , moduleSymbol           -- :: Source -> String -> IO (FunPtr a)
        , moduleClose            -- :: Module -> IO Bool
        , moduleError            -- :: IO String
        , withModule             -- :: Maybe String
                                 -- -> String
    	                     -- -> [ModuleFlags ]
    			     -- -> (Module -> IO a)
    			     -- -> IO a
        , withModule_            -- :: Maybe String
     			     -- -> String
     			     -- -> [ModuleFlags]
     			     -- -> (Module -> IO a)
     			     -- -> IO ()
        )
    where

    {-# LINE 60 "libraries/unix/System/Posix/DynamicLinker/Module.hsc" #-}

    import System.Posix.DynamicLinker
    import System.Posix.DynamicLinker.Common
    import Foreign.Ptr      ( Ptr, nullPtr, FunPtr )
    import System.Posix.Internals ( withFilePath )

    unModule              :: Module -> (Ptr ())
    unModule (Module adr)  = adr

    -- Opens a module (EXPORTED)
    --

    moduleOpen :: String -> [RTLDFlags] -> IO Module
    moduleOpen file flags = do
      modPtr <- withFilePath file $ \ modAddr -> c_dlopen modAddr (packRTLDFlags flags)
      if (modPtr == nullPtr)
          then moduleError >>= \ err -> ioError (userError ("dlopen: " ++ err))
          else return $ Module modPtr

    -- Gets a symbol pointer from a module (EXPORTED)
    --
    moduleSymbol :: Module -> String -> IO (FunPtr a)
    moduleSymbol file sym = dlsym (DLHandle (unModule file)) sym

    -- Closes a module (EXPORTED)
    --
    moduleClose     :: Module -> IO ()
    moduleClose file  = dlclose (DLHandle (unModule file))

    -- Gets a string describing the last module error (EXPORTED)
    --
    moduleError :: IO String
    moduleError  = dlerror

    -- Convenience function, cares for module open- & closing
    -- additionally returns status of `moduleClose' (EXPORTED)
    --
    withModule :: Maybe String
               -> String
    	   -> [RTLDFlags]
               -> (Module -> IO a)
    	   -> IO a
    withModule mdir file flags p = do
      let modPath = case mdir of
                      Nothing -> file
    	          Just dir  -> dir ++ if ((head (reverse dir)) == '/')
                                           then file
    				       else ('/':file)
      modu <- moduleOpen modPath flags
      result <- p modu
      moduleClose modu
      return result

    withModule_ :: Maybe String
                -> String
    	    -> [RTLDFlags]
                -> (Module -> IO a)
    	    -> IO ()
    withModule_ dir file flags p = withModule dir file flags p >>= \ _ -> return ()