/usr/lib/hugs/packages/base/Foreign/Marshal/Alloc.hs is in libhugs-base-bundled 98.200609.21-5.3ubuntu1.
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-----------------------------------------------------------------------------
-- |
-- Module : Foreign.Marshal.Alloc
-- Copyright : (c) The FFI task force 2001
-- License : BSD-style (see the file libraries/base/LICENSE)
--
-- Maintainer : ffi@haskell.org
-- Stability : provisional
-- Portability : portable
--
-- Marshalling support: basic routines for memory allocation
--
-----------------------------------------------------------------------------
module Foreign.Marshal.Alloc (
-- * Memory allocation
-- ** Local allocation
alloca, -- :: Storable a => (Ptr a -> IO b) -> IO b
allocaBytes, -- :: Int -> (Ptr a -> IO b) -> IO b
-- ** Dynamic allocation
malloc, -- :: Storable a => IO (Ptr a)
mallocBytes, -- :: Int -> IO (Ptr a)
realloc, -- :: Storable b => Ptr a -> IO (Ptr b)
reallocBytes, -- :: Ptr a -> Int -> IO (Ptr a)
free, -- :: Ptr a -> IO ()
finalizerFree -- :: FinalizerPtr a
) where
import Data.Maybe
import Foreign.Ptr ( Ptr, nullPtr, FunPtr )
import Foreign.C.Types ( CSize )
import Foreign.Storable ( Storable(sizeOf) )
import Control.Exception ( bracket )
import Hugs.Prelude ( IOException(IOError),
IOErrorType(ResourceExhausted) )
import Hugs.ForeignPtr ( FinalizerPtr )
-- exported functions
-- ------------------
-- |Allocate a block of memory that is sufficient to hold values of type
-- @a@. The size of the area allocated is determined by the 'sizeOf'
-- method from the instance of 'Storable' for the appropriate type.
--
-- The memory may be deallocated using 'free' or 'finalizerFree' when
-- no longer required.
--
malloc :: Storable a => IO (Ptr a)
malloc = doMalloc undefined
where
doMalloc :: Storable b => b -> IO (Ptr b)
doMalloc dummy = mallocBytes (sizeOf dummy)
-- |Allocate a block of memory of the given number of bytes.
-- The block of memory is sufficiently aligned for any of the basic
-- foreign types that fits into a memory block of the allocated size.
--
-- The memory may be deallocated using 'free' or 'finalizerFree' when
-- no longer required.
--
mallocBytes :: Int -> IO (Ptr a)
mallocBytes size = failWhenNULL "malloc" (_malloc (fromIntegral size))
-- |@'alloca' f@ executes the computation @f@, passing as argument
-- a pointer to a temporarily allocated block of memory sufficient to
-- hold values of type @a@.
--
-- The memory is freed when @f@ terminates (either normally or via an
-- exception), so the pointer passed to @f@ must /not/ be used after this.
--
alloca :: Storable a => (Ptr a -> IO b) -> IO b
alloca = doAlloca undefined
where
doAlloca :: Storable a' => a' -> (Ptr a' -> IO b') -> IO b'
doAlloca dummy = allocaBytes (sizeOf dummy)
-- |@'allocaBytes' n f@ executes the computation @f@, passing as argument
-- a pointer to a temporarily allocated block of memory of @n@ bytes.
-- The block of memory is sufficiently aligned for any of the basic
-- foreign types that fits into a memory block of the allocated size.
--
-- The memory is freed when @f@ terminates (either normally or via an
-- exception), so the pointer passed to @f@ must /not/ be used after this.
--
allocaBytes :: Int -> (Ptr a -> IO b) -> IO b
allocaBytes size = bracket (mallocBytes size) free
-- |Resize a memory area that was allocated with 'malloc' or 'mallocBytes'
-- to the size needed to store values of type @b@. The returned pointer
-- may refer to an entirely different memory area, but will be suitably
-- aligned to hold values of type @b@. The contents of the referenced
-- memory area will be the same as of the original pointer up to the
-- minimum of the original size and the size of values of type @b@.
--
-- If the argument to 'realloc' is 'nullPtr', 'realloc' behaves like
-- 'malloc'.
--
realloc :: Storable b => Ptr a -> IO (Ptr b)
realloc = doRealloc undefined
where
doRealloc :: Storable b' => b' -> Ptr a' -> IO (Ptr b')
doRealloc dummy ptr = let
size = fromIntegral (sizeOf dummy)
in
failWhenNULL "realloc" (_realloc ptr size)
-- |Resize a memory area that was allocated with 'malloc' or 'mallocBytes'
-- to the given size. The returned pointer may refer to an entirely
-- different memory area, but will be sufficiently aligned for any of the
-- basic foreign types that fits into a memory block of the given size.
-- The contents of the referenced memory area will be the same as of
-- the original pointer up to the minimum of the original size and the
-- given size.
--
-- If the pointer argument to 'reallocBytes' is 'nullPtr', 'reallocBytes'
-- behaves like 'malloc'. If the requested size is 0, 'reallocBytes'
-- behaves like 'free'.
--
reallocBytes :: Ptr a -> Int -> IO (Ptr a)
reallocBytes ptr 0 = do free ptr; return nullPtr
reallocBytes ptr size =
failWhenNULL "realloc" (_realloc ptr (fromIntegral size))
-- |Free a block of memory that was allocated with 'malloc',
-- 'mallocBytes', 'realloc', 'reallocBytes', 'Foreign.Marshal.Utils.new'
-- or any of the @new@/X/ functions in "Foreign.Marshal.Array" or
-- "Foreign.C.String".
--
free :: Ptr a -> IO ()
free = _free
-- auxilliary routines
-- -------------------
-- asserts that the pointer returned from the action in the second argument is
-- non-null
--
failWhenNULL :: String -> IO (Ptr a) -> IO (Ptr a)
failWhenNULL name f = do
addr <- f
if addr == nullPtr
then ioError (IOError Nothing ResourceExhausted name
"out of memory" Nothing)
else return addr
-- basic C routines needed for memory allocation
--
foreign import ccall unsafe "stdlib.h malloc" _malloc :: CSize -> IO (Ptr a)
foreign import ccall unsafe "stdlib.h realloc" _realloc :: Ptr a -> CSize -> IO (Ptr b)
foreign import ccall unsafe "stdlib.h free" _free :: Ptr a -> IO ()
-- | A pointer to a foreign function equivalent to 'free', which may be
-- used as a finalizer (cf 'Foreign.ForeignPtr.ForeignPtr') for storage
-- allocated with 'malloc', 'mallocBytes', 'realloc' or 'reallocBytes'.
foreign import ccall unsafe "stdlib.h &free" finalizerFree :: FinalizerPtr a
|