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 */ 105