1 {-# OPTIONS_GHC -XNoImplicitPrelude #-}
2 -----------------------------------------------------------------------------
4 -- Module : Foreign.Marshal.Alloc
5 -- Copyright : (c) The FFI task force 2001
6 -- License : BSD-style (see the file libraries/base/LICENSE)
8 -- Maintainer : ffi@haskell.org
9 -- Stability : provisional
10 -- Portability : portable
12 -- Marshalling support: basic routines for memory allocation
14 -----------------------------------------------------------------------------
16 module Foreign.Marshal.Alloc (
17 -- * Memory allocation
18 -- ** Local allocation
19 alloca, -- :: Storable a => (Ptr a -> IO b) -> IO b
20 allocaBytes, -- :: Int -> (Ptr a -> IO b) -> IO b
22 -- ** Dynamic allocation
23 malloc, -- :: Storable a => IO (Ptr a)
24 mallocBytes, -- :: Int -> IO (Ptr a)
26 realloc, -- :: Storable b => Ptr a -> IO (Ptr b)
27 reallocBytes, -- :: Ptr a -> Int -> IO (Ptr a)
29 free, -- :: Ptr a -> IO ()
30 finalizerFree -- :: FinalizerPtr a
34 import Foreign.C.Types ( CSize )
35 import Foreign.Storable ( Storable(sizeOf) )
37 #ifndef __GLASGOW_HASKELL__
38 import Foreign.Ptr ( Ptr, nullPtr, FunPtr )
41 #ifdef __GLASGOW_HASKELL__
42 import Foreign.ForeignPtr ( FinalizerPtr )
49 #elif defined(__NHC__)
50 import NHC.FFI ( FinalizerPtr, CInt(..) )
53 import Control.Exception ( bracket )
57 import Hugs.Prelude ( IOException(IOError),
58 IOErrorType(ResourceExhausted) )
59 import Hugs.ForeignPtr ( FinalizerPtr )
66 -- |Allocate a block of memory that is sufficient to hold values of type
67 -- @a@. The size of the area allocated is determined by the 'sizeOf'
68 -- method from the instance of 'Storable' for the appropriate type.
70 -- The memory may be deallocated using 'free' or 'finalizerFree' when
71 -- no longer required.
73 malloc :: Storable a => IO (Ptr a)
74 malloc = doMalloc undefined
76 doMalloc :: Storable b => b -> IO (Ptr b)
77 doMalloc dummy = mallocBytes (sizeOf dummy)
79 -- |Allocate a block of memory of the given number of bytes.
80 -- The block of memory is sufficiently aligned for any of the basic
81 -- foreign types that fits into a memory block of the allocated size.
83 -- The memory may be deallocated using 'free' or 'finalizerFree' when
84 -- no longer required.
86 mallocBytes :: Int -> IO (Ptr a)
87 mallocBytes size = failWhenNULL "malloc" (_malloc (fromIntegral size))
89 -- |@'alloca' f@ executes the computation @f@, passing as argument
90 -- a pointer to a temporarily allocated block of memory sufficient to
91 -- hold values of type @a@.
93 -- The memory is freed when @f@ terminates (either normally or via an
94 -- exception), so the pointer passed to @f@ must /not/ be used after this.
96 alloca :: Storable a => (Ptr a -> IO b) -> IO b
97 alloca = doAlloca undefined
99 doAlloca :: Storable a' => a' -> (Ptr a' -> IO b') -> IO b'
100 doAlloca dummy = allocaBytes (sizeOf dummy)
102 -- |@'allocaBytes' n f@ executes the computation @f@, passing as argument
103 -- a pointer to a temporarily allocated block of memory of @n@ bytes.
104 -- The block of memory is sufficiently aligned for any of the basic
105 -- foreign types that fits into a memory block of the allocated size.
107 -- The memory is freed when @f@ terminates (either normally or via an
108 -- exception), so the pointer passed to @f@ must /not/ be used after this.
110 #ifdef __GLASGOW_HASKELL__
111 allocaBytes :: Int -> (Ptr a -> IO b) -> IO b
112 allocaBytes (I# size) action = IO $ \ s ->
113 case newPinnedByteArray# size s of { (# s, mbarr# #) ->
114 case unsafeFreezeByteArray# mbarr# s of { (# s, barr# #) ->
115 let addr = Ptr (byteArrayContents# barr#) in
116 case action addr of { IO action ->
117 case action s of { (# s, r #) ->
118 case touch# barr# s of { s ->
122 allocaBytes :: Int -> (Ptr a -> IO b) -> IO b
123 allocaBytes size = bracket (mallocBytes size) free
126 -- |Resize a memory area that was allocated with 'malloc' or 'mallocBytes'
127 -- to the size needed to store values of type @b@. The returned pointer
128 -- may refer to an entirely different memory area, but will be suitably
129 -- aligned to hold values of type @b@. The contents of the referenced
130 -- memory area will be the same as of the original pointer up to the
131 -- minimum of the original size and the size of values of type @b@.
133 -- If the argument to 'realloc' is 'nullPtr', 'realloc' behaves like
136 realloc :: Storable b => Ptr a -> IO (Ptr b)
137 realloc = doRealloc undefined
139 doRealloc :: Storable b' => b' -> Ptr a' -> IO (Ptr b')
140 doRealloc dummy ptr = let
141 size = fromIntegral (sizeOf dummy)
143 failWhenNULL "realloc" (_realloc ptr size)
145 -- |Resize a memory area that was allocated with 'malloc' or 'mallocBytes'
146 -- to the given size. The returned pointer may refer to an entirely
147 -- different memory area, but will be sufficiently aligned for any of the
148 -- basic foreign types that fits into a memory block of the given size.
149 -- The contents of the referenced memory area will be the same as of
150 -- the original pointer up to the minimum of the original size and the
153 -- If the pointer argument to 'reallocBytes' is 'nullPtr', 'reallocBytes'
154 -- behaves like 'malloc'. If the requested size is 0, 'reallocBytes'
155 -- behaves like 'free'.
157 reallocBytes :: Ptr a -> Int -> IO (Ptr a)
158 reallocBytes ptr 0 = do free ptr; return nullPtr
159 reallocBytes ptr size =
160 failWhenNULL "realloc" (_realloc ptr (fromIntegral size))
162 -- |Free a block of memory that was allocated with 'malloc',
163 -- 'mallocBytes', 'realloc', 'reallocBytes', 'Foreign.Marshal.Utils.new'
164 -- or any of the @new@/X/ functions in "Foreign.Marshal.Array" or
165 -- "Foreign.C.String".
167 free :: Ptr a -> IO ()
171 -- auxilliary routines
172 -- -------------------
174 -- asserts that the pointer returned from the action in the second argument is
177 failWhenNULL :: String -> IO (Ptr a) -> IO (Ptr a)
178 failWhenNULL name f = do
181 #if __GLASGOW_HASKELL__ || __HUGS__
182 then ioError (IOError Nothing ResourceExhausted name
183 "out of memory" Nothing)
185 then ioError (userError (name++": out of memory"))
189 -- basic C routines needed for memory allocation
191 foreign import ccall unsafe "stdlib.h malloc" _malloc :: CSize -> IO (Ptr a)
192 foreign import ccall unsafe "stdlib.h realloc" _realloc :: Ptr a -> CSize -> IO (Ptr b)
193 foreign import ccall unsafe "stdlib.h free" _free :: Ptr a -> IO ()
195 -- | A pointer to a foreign function equivalent to 'free', which may be
196 -- used as a finalizer (cf 'Foreign.ForeignPtr.ForeignPtr') for storage
197 -- allocated with 'malloc', 'mallocBytes', 'realloc' or 'reallocBytes'.
198 foreign import ccall unsafe "stdlib.h &free" finalizerFree :: FinalizerPtr a