93 lines
2.5 KiB
Haskell
93 lines
2.5 KiB
Haskell
#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.DynamicLinker.Common
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-- Copyright : (c) Volker Stolz <vs@foldr.org> 2003
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-- License : BSD-style (see the file libraries/base/LICENSE)
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--
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-- Maintainer : vs@foldr.org
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-- Stability : provisional
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-- Portability : non-portable (requires POSIX)
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--
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-- Dynamic linker support through dlopen()
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-----------------------------------------------------------------------------
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module System.Posix.DynamicLinker.Common (
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module System.Posix.DynamicLinker.Prim,
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dlsym,
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dlerror,
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dlclose,
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undl,
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throwDLErrorIf,
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Module(..)
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)
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-- Usage:
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-- ******
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--
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-- Let's assume you want to open a local shared library \'foo\' (.\/libfoo.so)
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-- offering a function
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-- @char \* mogrify (char\*,int)@
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-- and invoke @str = mogrify("test",1)@:
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--
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--
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-- type Fun = CString -> Int -> IO CString
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-- foreign import dynamic unsafe fun__ :: FunPtr Fun -> Fun
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--
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-- withDL "libfoo.so" [RTLD_NOW] \$ \\ mod -> do
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-- funptr <- dlsym mod "mogrify"
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-- let fun = fun__ funptr
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-- withCString "test" \$ \\ str -> do
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-- strptr <- fun str 1
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-- strstr <- peekCString strptr
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-- ...
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--
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where
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#include "HsUnix.h"
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import System.Posix.DynamicLinker.Prim
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import Foreign
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import Foreign.C
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dlclose :: DL -> IO ()
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dlclose (DLHandle h) = throwDLErrorIf_ "dlclose" (/= 0) $ c_dlclose h
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dlclose h = error $ "dlclose: invalid argument" ++ (show h)
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dlerror :: IO String
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dlerror = c_dlerror >>= peekCString
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-- |'dlsym' returns the address binding of the symbol described in @symbol@,
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-- as it occurs in the shared object identified by @source@.
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dlsym :: DL -> String -> IO (FunPtr a)
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dlsym source symbol = do
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withCAString symbol $ \ s -> do
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throwDLErrorIf "dlsym" (== nullFunPtr) $ c_dlsym (packDL source) s
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-- |'undl' obtains the raw handle. You mustn't do something like
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-- @withDL mod flags $ liftM undl >>= \ p -> use p@
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undl :: DL -> Ptr ()
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undl = packDL
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throwDLErrorIf :: String -> (a -> Bool) -> IO a -> IO a
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throwDLErrorIf s p f = do
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r <- f
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if (p r)
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then dlerror >>= \ err -> ioError (userError ( s ++ ": " ++ err))
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else return r
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throwDLErrorIf_ :: String -> (a -> Bool) -> IO a -> IO ()
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throwDLErrorIf_ s p f = throwDLErrorIf s p f >> return ()
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-- abstract handle for dynamically loaded module (EXPORTED)
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--
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newtype Module = Module (Ptr ())
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