python (3.11.7)
1 /* The PyMem_ family: low-level memory allocation interfaces.
2 See objimpl.h for the PyObject_ memory family.
3 */
4
5 #ifndef Py_PYMEM_H
6 #define Py_PYMEM_H
7
8 #include "pyport.h"
9
10 #ifdef __cplusplus
11 extern "C" {
12 #endif
13
14 /* BEWARE:
15
16 Each interface exports both functions and macros. Extension modules should
17 use the functions, to ensure binary compatibility across Python versions.
18 Because the Python implementation is free to change internal details, and
19 the macros may (or may not) expose details for speed, if you do use the
20 macros you must recompile your extensions with each Python release.
21
22 Never mix calls to PyMem_ with calls to the platform malloc/realloc/
23 calloc/free. For example, on Windows different DLLs may end up using
24 different heaps, and if you use PyMem_Malloc you'll get the memory from the
25 heap used by the Python DLL; it could be a disaster if you free()'ed that
26 directly in your own extension. Using PyMem_Free instead ensures Python
27 can return the memory to the proper heap. As another example, in
28 a debug build (Py_DEBUG macro), Python wraps all calls to all PyMem_ and
29 PyObject_ memory functions in special debugging wrappers that add additional
30 debugging info to dynamic memory blocks. The system routines have no idea
31 what to do with that stuff, and the Python wrappers have no idea what to do
32 with raw blocks obtained directly by the system routines then.
33
34 The GIL must be held when using these APIs.
35 */
36
37 /*
38 * Raw memory interface
39 * ====================
40 */
41
42 /* Functions
43
44 Functions supplying platform-independent semantics for malloc/realloc/
45 free. These functions make sure that allocating 0 bytes returns a distinct
46 non-NULL pointer (whenever possible -- if we're flat out of memory, NULL
47 may be returned), even if the platform malloc and realloc don't.
48 Returned pointers must be checked for NULL explicitly. No action is
49 performed on failure (no exception is set, no warning is printed, etc).
50 */
51
52 PyAPI_FUNC(void *) PyMem_Malloc(size_t size);
53 PyAPI_FUNC(void *) PyMem_Calloc(size_t nelem, size_t elsize);
54 PyAPI_FUNC(void *) PyMem_Realloc(void *ptr, size_t new_size);
55 PyAPI_FUNC(void) PyMem_Free(void *ptr);
56
57 /*
58 * Type-oriented memory interface
59 * ==============================
60 *
61 * Allocate memory for n objects of the given type. Returns a new pointer
62 * or NULL if the request was too large or memory allocation failed. Use
63 * these macros rather than doing the multiplication yourself so that proper
64 * overflow checking is always done.
65 */
66
67 #define PyMem_New(type, n) \
68 ( ((size_t)(n) > PY_SSIZE_T_MAX / sizeof(type)) ? NULL : \
69 ( (type *) PyMem_Malloc((n) * sizeof(type)) ) )
70
71 /*
72 * The value of (p) is always clobbered by this macro regardless of success.
73 * The caller MUST check if (p) is NULL afterwards and deal with the memory
74 * error if so. This means the original value of (p) MUST be saved for the
75 * caller's memory error handler to not lose track of it.
76 */
77 #define PyMem_Resize(p, type, n) \
78 ( (p) = ((size_t)(n) > PY_SSIZE_T_MAX / sizeof(type)) ? NULL : \
79 (type *) PyMem_Realloc((p), (n) * sizeof(type)) )
80
81
82 // Deprecated aliases only kept for backward compatibility.
83 // PyMem_Del and PyMem_DEL are defined with no parameter to be able to use
84 // them as function pointers (ex: dealloc = PyMem_Del).
85 #define PyMem_MALLOC(n) PyMem_Malloc(n)
86 #define PyMem_NEW(type, n) PyMem_New(type, n)
87 #define PyMem_REALLOC(p, n) PyMem_Realloc(p, n)
88 #define PyMem_RESIZE(p, type, n) PyMem_Resize(p, type, n)
89 #define PyMem_FREE(p) PyMem_Free(p)
90 #define PyMem_Del PyMem_Free
91 #define PyMem_DEL PyMem_Free
92
93
94 #ifndef Py_LIMITED_API
95 # define Py_CPYTHON_PYMEM_H
96 # include "cpython/pymem.h"
97 # undef Py_CPYTHON_PYMEM_H
98 #endif
99
100 #ifdef __cplusplus
101 }
102 #endif
103
104 #endif /* !Py_PYMEM_H */
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