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 PYMALLOC_DEBUG mode, Python wraps all calls to all PyMem_ and PyObject_ 29 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_Realloc(void *ptr, size_t new_size); 54 PyAPI_FUNC(void) PyMem_Free(void *ptr); 55 56 /* Macros. */ 57 58 /* PyMem_MALLOC(0) means malloc(1). Some systems would return NULL 59 for malloc(0), which would be treated as an error. Some platforms 60 would return a pointer with no memory behind it, which would break 61 pymalloc. To solve these problems, allocate an extra byte. */ 62 /* Returns NULL to indicate error if a negative size or size larger than 63 Py_ssize_t can represent is supplied. Helps prevents security holes. */ 64 #define PyMem_MALLOC(n) PyMem_Malloc(n) 65 #define PyMem_REALLOC(p, n) PyMem_Realloc(p, n) 66 #define PyMem_FREE(p) PyMem_Free(p) 67 68 /* 69 * Type-oriented memory interface 70 * ============================== 71 * 72 * Allocate memory for n objects of the given type. Returns a new pointer 73 * or NULL if the request was too large or memory allocation failed. Use 74 * these macros rather than doing the multiplication yourself so that proper 75 * overflow checking is always done. 76 */ 77 78 #define PyMem_New(type, n) \ 79 ( ((size_t)(n) > PY_SSIZE_T_MAX / sizeof(type)) ? NULL : \ 80 ( (type *) PyMem_Malloc((n) * sizeof(type)) ) ) 81 #define PyMem_NEW(type, n) \ 82 ( ((size_t)(n) > PY_SSIZE_T_MAX / sizeof(type)) ? NULL : \ 83 ( (type *) PyMem_MALLOC((n) * sizeof(type)) ) ) 84 85 /* 86 * The value of (p) is always clobbered by this macro regardless of success. 87 * The caller MUST check if (p) is NULL afterwards and deal with the memory 88 * error if so. This means the original value of (p) MUST be saved for the 89 * caller's memory error handler to not lose track of it. 90 */ 91 #define PyMem_Resize(p, type, n) \ 92 ( (p) = ((size_t)(n) > PY_SSIZE_T_MAX / sizeof(type)) ? NULL : \ 93 (type *) PyMem_Realloc((p), (n) * sizeof(type)) ) 94 #define PyMem_RESIZE(p, type, n) \ 95 ( (p) = ((size_t)(n) > PY_SSIZE_T_MAX / sizeof(type)) ? NULL : \ 96 (type *) PyMem_REALLOC((p), (n) * sizeof(type)) ) 97 98 /* PyMem{Del,DEL} are left over from ancient days, and shouldn't be used 99 * anymore. They're just confusing aliases for PyMem_{Free,FREE} now. 100 */ 101 #define PyMem_Del PyMem_Free 102 #define PyMem_DEL PyMem_FREE 103 104 /* bpo-35053: expose _Py_tracemalloc_config for performance: 105 _Py_NewReference() needs an efficient check to test if tracemalloc is 106 tracing. 107 108 It has to be defined in pymem.h, before object.h is included. */ 109 struct _PyTraceMalloc_Config { 110 /* Module initialized? 111 Variable protected by the GIL */ 112 enum { 113 TRACEMALLOC_NOT_INITIALIZED, 114 TRACEMALLOC_INITIALIZED, 115 TRACEMALLOC_FINALIZED 116 } initialized; 117 118 /* Is tracemalloc tracing memory allocations? 119 Variable protected by the GIL */ 120 int tracing; 121 122 /* limit of the number of frames in a traceback, 1 by default. 123 Variable protected by the GIL. */ 124 int max_nframe; 125 126 /* use domain in trace key? 127 Variable protected by the GIL. */ 128 int use_domain; 129 }; 130 131 PyAPI_DATA(struct _PyTraceMalloc_Config) _Py_tracemalloc_config; 132 133 #define _PyTraceMalloc_Config_INIT \ 134 {.initialized = TRACEMALLOC_NOT_INITIALIZED, \ 135 .tracing = 0, \ 136 .max_nframe = 1, \ 137 .use_domain = 0} 138 139 140 #ifndef Py_LIMITED_API 141 # define Py_CPYTHON_PYMEM_H 142 # include "cpython/pymem.h" 143 # undef Py_CPYTHON_PYMEM_H 144 #endif 145 146 #ifdef __cplusplus 147 } 148 #endif 149 150 #endif /* !Py_PYMEM_H */ 151