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1 /* The PyMem_ family: low-level memory allocation interfaces.
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2 See objimpl.h for the PyObject_ memory family.
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3 */
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4
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5 #ifndef Py_PYMEM_H
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6 #define Py_PYMEM_H
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7
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8 #include "pyport.h"
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9
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10 #ifdef __cplusplus
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11 extern "C" {
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12 #endif
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13
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14 /* BEWARE:
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15
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16 Each interface exports both functions and macros. Extension modules should
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17 use the functions, to ensure binary compatibility across Python versions.
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18 Because the Python implementation is free to change internal details, and
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19 the macros may (or may not) expose details for speed, if you do use the
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20 macros you must recompile your extensions with each Python release.
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21
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22 Never mix calls to PyMem_ with calls to the platform malloc/realloc/
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23 calloc/free. For example, on Windows different DLLs may end up using
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24 different heaps, and if you use PyMem_Malloc you'll get the memory from the
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25 heap used by the Python DLL; it could be a disaster if you free()'ed that
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26 directly in your own extension. Using PyMem_Free instead ensures Python
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27 can return the memory to the proper heap. As another example, in
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28 PYMALLOC_DEBUG mode, Python wraps all calls to all PyMem_ and PyObject_
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29 memory functions in special debugging wrappers that add additional
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30 debugging info to dynamic memory blocks. The system routines have no idea
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31 what to do with that stuff, and the Python wrappers have no idea what to do
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32 with raw blocks obtained directly by the system routines then.
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33
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34 The GIL must be held when using these APIs.
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35 */
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36
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37 /*
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38 * Raw memory interface
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39 * ====================
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40 */
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41
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42 /* Functions
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43
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44 Functions supplying platform-independent semantics for malloc/realloc/
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45 free. These functions make sure that allocating 0 bytes returns a distinct
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46 non-NULL pointer (whenever possible -- if we're flat out of memory, NULL
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47 may be returned), even if the platform malloc and realloc don't.
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48 Returned pointers must be checked for NULL explicitly. No action is
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49 performed on failure (no exception is set, no warning is printed, etc).
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50 */
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51
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52 PyAPI_FUNC(void *) PyMem_Malloc(size_t size);
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53 PyAPI_FUNC(void *) PyMem_Realloc(void *ptr, size_t new_size);
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54 PyAPI_FUNC(void) PyMem_Free(void *ptr);
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55
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56 /* Macros. */
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57
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58 /* PyMem_MALLOC(0) means malloc(1). Some systems would return NULL
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59 for malloc(0), which would be treated as an error. Some platforms
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60 would return a pointer with no memory behind it, which would break
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61 pymalloc. To solve these problems, allocate an extra byte. */
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62 /* Returns NULL to indicate error if a negative size or size larger than
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63 Py_ssize_t can represent is supplied. Helps prevents security holes. */
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64 #define PyMem_MALLOC(n) PyMem_Malloc(n)
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65 #define PyMem_REALLOC(p, n) PyMem_Realloc(p, n)
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66 #define PyMem_FREE(p) PyMem_Free(p)
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67
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68 /*
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69 * Type-oriented memory interface
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70 * ==============================
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71 *
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72 * Allocate memory for n objects of the given type. Returns a new pointer
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73 * or NULL if the request was too large or memory allocation failed. Use
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74 * these macros rather than doing the multiplication yourself so that proper
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75 * overflow checking is always done.
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76 */
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77
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78 #define PyMem_New(type, n) \
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79 ( ((size_t)(n) > PY_SSIZE_T_MAX / sizeof(type)) ? NULL : \
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80 ( (type *) PyMem_Malloc((n) * sizeof(type)) ) )
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81 #define PyMem_NEW(type, n) \
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82 ( ((size_t)(n) > PY_SSIZE_T_MAX / sizeof(type)) ? NULL : \
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83 ( (type *) PyMem_MALLOC((n) * sizeof(type)) ) )
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84
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85 /*
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86 * The value of (p) is always clobbered by this macro regardless of success.
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87 * The caller MUST check if (p) is NULL afterwards and deal with the memory
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88 * error if so. This means the original value of (p) MUST be saved for the
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89 * caller's memory error handler to not lose track of it.
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90 */
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91 #define PyMem_Resize(p, type, n) \
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92 ( (p) = ((size_t)(n) > PY_SSIZE_T_MAX / sizeof(type)) ? NULL : \
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93 (type *) PyMem_Realloc((p), (n) * sizeof(type)) )
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94 #define PyMem_RESIZE(p, type, n) \
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95 ( (p) = ((size_t)(n) > PY_SSIZE_T_MAX / sizeof(type)) ? NULL : \
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96 (type *) PyMem_REALLOC((p), (n) * sizeof(type)) )
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97
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98 /* PyMem{Del,DEL} are left over from ancient days, and shouldn't be used
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99 * anymore. They're just confusing aliases for PyMem_{Free,FREE} now.
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100 */
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101 #define PyMem_Del PyMem_Free
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102 #define PyMem_DEL PyMem_FREE
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103
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104 /* bpo-35053: expose _Py_tracemalloc_config for performance:
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105 _Py_NewReference() needs an efficient check to test if tracemalloc is
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106 tracing.
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107
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108 It has to be defined in pymem.h, before object.h is included. */
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109 struct _PyTraceMalloc_Config {
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110 /* Module initialized?
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111 Variable protected by the GIL */
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112 enum {
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113 TRACEMALLOC_NOT_INITIALIZED,
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114 TRACEMALLOC_INITIALIZED,
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115 TRACEMALLOC_FINALIZED
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116 } initialized;
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117
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118 /* Is tracemalloc tracing memory allocations?
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119 Variable protected by the GIL */
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120 int tracing;
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121
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122 /* limit of the number of frames in a traceback, 1 by default.
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123 Variable protected by the GIL. */
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124 int max_nframe;
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125
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126 /* use domain in trace key?
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127 Variable protected by the GIL. */
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128 int use_domain;
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129 };
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130
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131 PyAPI_DATA(struct _PyTraceMalloc_Config) _Py_tracemalloc_config;
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132
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133 #define _PyTraceMalloc_Config_INIT \
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134 {.initialized = TRACEMALLOC_NOT_INITIALIZED, \
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135 .tracing = 0, \
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136 .max_nframe = 1, \
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137 .use_domain = 0}
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138
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139
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140 #ifndef Py_LIMITED_API
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141 # define Py_CPYTHON_PYMEM_H
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142 # include "cpython/pymem.h"
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143 # undef Py_CPYTHON_PYMEM_H
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144 #endif
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145
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146 #ifdef __cplusplus
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147 }
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148 #endif
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149
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150 #endif /* !Py_PYMEM_H */
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