{-# LINE 1 "Magic/Utils.hsc" #-}
{- -*- Mode: haskell; -*-
Haskell magic Interface
Copyright (C) 2005 John Goerzen <jgoerzen@complete.org>

This code is under a 3-clause BSD license; see COPYING for details.
-}

{- |
   Module     : Magic.Utils
   Copyright  : Copyright (C) 2005 John Goerzen
   License    : BSD

   Maintainer : John Goerzen,
   Maintainer : jgoerzen\@complete.org
   Stability  : provisional
   Portability: portable

Utils

Written by John Goerzen, jgoerzen\@complete.org
-}

module Magic.Utils (flaglist2int, fromMagicPtr, withMagicPtr, checkIntError,
                    throwErrorIfNull)
where

import Foreign
import Foreign.C.Error
import Foreign.C.String
import Foreign.ForeignPtr
import Magic.TypesLL
import Magic.Types
import Data.Bits
import Foreign.C.Types
import Magic.Data

flaglist2int :: [MagicFlag] -> CInt
flaglist2int :: [MagicFlag] -> CInt
flaglist2int [MagicFlag]
mfl =
    (CInt -> MagicFlag -> CInt) -> CInt -> [MagicFlag] -> CInt
forall b a. (b -> a -> b) -> b -> [a] -> b
forall (t :: * -> *) b a.
Foldable t =>
(b -> a -> b) -> b -> t a -> b
foldl (\CInt
c MagicFlag
f -> CInt
c CInt -> CInt -> CInt
forall a. Bits a => a -> a -> a
.|. (Int -> CInt
forall a b. (Integral a, Num b) => a -> b
fromIntegral (Int -> CInt) -> (MagicFlag -> Int) -> MagicFlag -> CInt
forall b c a. (b -> c) -> (a -> b) -> a -> c
. MagicFlag -> Int
forall a. Enum a => a -> Int
fromEnum (MagicFlag -> CInt) -> MagicFlag -> CInt
forall a b. (a -> b) -> a -> b
$ MagicFlag
f)) CInt
0 [MagicFlag]
mfl

fromMagicPtr :: String -> IO (Ptr CMagic) -> IO Magic
fromMagicPtr :: String -> IO (Ptr CMagic) -> IO Magic
fromMagicPtr String
caller IO (Ptr CMagic)
action =
    do ptr <- String -> IO (Ptr CMagic) -> IO (Ptr CMagic)
forall a. String -> IO (Ptr a) -> IO (Ptr a)
throwErrnoIfNull String
caller IO (Ptr CMagic)
action
       newForeignPtr magic_close ptr

throwErrorIfNull :: String -> Magic -> IO (Ptr a) -> IO (Ptr a)
throwErrorIfNull :: forall a. String -> Magic -> IO (Ptr a) -> IO (Ptr a)
throwErrorIfNull String
caller Magic
m IO (Ptr a)
action =
    do res <- IO (Ptr a)
action
       if res == nullPtr
          then throwError caller m
          else return res

withMagicPtr :: Magic -> (Ptr CMagic -> IO a) -> IO a
withMagicPtr :: forall a. Magic -> (Ptr CMagic -> IO a) -> IO a
withMagicPtr Magic
m = Magic -> (Ptr CMagic -> IO a) -> IO a
forall a b. ForeignPtr a -> (Ptr a -> IO b) -> IO b
withForeignPtr Magic
m

throwError :: String -> Magic -> IO a
throwError :: forall a. String -> Magic -> IO a
throwError String
caller Magic
m = Magic -> (Ptr CMagic -> IO a) -> IO a
forall a. Magic -> (Ptr CMagic -> IO a) -> IO a
withMagicPtr Magic
m (\Ptr CMagic
cmagic ->
               do errormsg <- Ptr CMagic -> IO CString
magic_error Ptr CMagic
cmagic
                  if errormsg /= nullPtr
                     then do em <- peekCString errormsg
                             fail $ caller ++ ": " ++ em
                     else fail $ caller ++ ": got error code but no error message"
                                     )

checkIntError :: String -> Magic -> IO CInt -> IO ()
checkIntError :: String -> Magic -> IO CInt -> IO ()
checkIntError String
caller Magic
m IO CInt
action = 
    do res <- IO CInt
action
       if res == 0
          then return ()
          else throwError caller m


foreign import ccall unsafe "magic.h &magic_close"
  magic_close :: FunPtr (Ptr CMagic -> IO ())

foreign import ccall unsafe "magic.h magic_error"
  magic_error :: Ptr CMagic -> IO CString