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1 #ifndef Py_CPYTHON_OBJECT_H
2 #  error "this header file must not be included directly"
3 #endif
4 
5 #ifdef __cplusplus
6 extern "C" {
7 #endif
8 
9 PyAPI_FUNC(void) _Py_NewReference(PyObject *op);
10 
11 #ifdef Py_TRACE_REFS
12 /* Py_TRACE_REFS is such major surgery that we call external routines. */
13 PyAPI_FUNC(void) _Py_ForgetReference(PyObject *);
14 #endif
15 
16 /* Update the Python traceback of an object. This function must be called
17    when a memory block is reused from a free list. */
18 PyAPI_FUNC(int) _PyTraceMalloc_NewReference(PyObject *op);
19 
20 #ifdef Py_REF_DEBUG
21 PyAPI_FUNC(Py_ssize_t) _Py_GetRefTotal(void);
22 #endif
23 
24 
25 /********************* String Literals ****************************************/
26 /* This structure helps managing static strings. The basic usage goes like this:
27    Instead of doing
28 
29        r = PyObject_CallMethod(o, "foo", "args", ...);
30 
31    do
32 
33        _Py_IDENTIFIER(foo);
34        ...
35        r = _PyObject_CallMethodId(o, &PyId_foo, "args", ...);
36 
37    PyId_foo is a static variable, either on block level or file level. On first
38    usage, the string "foo" is interned, and the structures are linked. On interpreter
39    shutdown, all strings are released.
40 
41    Alternatively, _Py_static_string allows choosing the variable name.
42    _PyUnicode_FromId returns a borrowed reference to the interned string.
43    _PyObject_{Get,Set,Has}AttrId are __getattr__ versions using _Py_Identifier*.
44 */
45 typedef struct _Py_Identifier {
46     struct _Py_Identifier *next;
47     const char* string;
48     PyObject *object;
49 } _Py_Identifier;
50 
51 #define _Py_static_string_init(value) { .next = NULL, .string = value, .object = NULL }
52 #define _Py_static_string(varname, value)  static _Py_Identifier varname = _Py_static_string_init(value)
53 #define _Py_IDENTIFIER(varname) _Py_static_string(PyId_##varname, #varname)
54 
55 /* buffer interface */
56 typedef struct bufferinfo {
57     void *buf;
58     PyObject *obj;        /* owned reference */
59     Py_ssize_t len;
60     Py_ssize_t itemsize;  /* This is Py_ssize_t so it can be
61                              pointed to by strides in simple case.*/
62     int readonly;
63     int ndim;
64     char *format;
65     Py_ssize_t *shape;
66     Py_ssize_t *strides;
67     Py_ssize_t *suboffsets;
68     void *internal;
69 } Py_buffer;
70 
71 typedef int (*getbufferproc)(PyObject *, Py_buffer *, int);
72 typedef void (*releasebufferproc)(PyObject *, Py_buffer *);
73 
74 typedef PyObject *(*vectorcallfunc)(PyObject *callable, PyObject *const *args,
75                                     size_t nargsf, PyObject *kwnames);
76 
77 /* Maximum number of dimensions */
78 #define PyBUF_MAX_NDIM 64
79 
80 /* Flags for getting buffers */
81 #define PyBUF_SIMPLE 0
82 #define PyBUF_WRITABLE 0x0001
83 /*  we used to include an E, backwards compatible alias  */
84 #define PyBUF_WRITEABLE PyBUF_WRITABLE
85 #define PyBUF_FORMAT 0x0004
86 #define PyBUF_ND 0x0008
87 #define PyBUF_STRIDES (0x0010 | PyBUF_ND)
88 #define PyBUF_C_CONTIGUOUS (0x0020 | PyBUF_STRIDES)
89 #define PyBUF_F_CONTIGUOUS (0x0040 | PyBUF_STRIDES)
90 #define PyBUF_ANY_CONTIGUOUS (0x0080 | PyBUF_STRIDES)
91 #define PyBUF_INDIRECT (0x0100 | PyBUF_STRIDES)
92 
93 #define PyBUF_CONTIG (PyBUF_ND | PyBUF_WRITABLE)
94 #define PyBUF_CONTIG_RO (PyBUF_ND)
95 
96 #define PyBUF_STRIDED (PyBUF_STRIDES | PyBUF_WRITABLE)
97 #define PyBUF_STRIDED_RO (PyBUF_STRIDES)
98 
99 #define PyBUF_RECORDS (PyBUF_STRIDES | PyBUF_WRITABLE | PyBUF_FORMAT)
100 #define PyBUF_RECORDS_RO (PyBUF_STRIDES | PyBUF_FORMAT)
101 
102 #define PyBUF_FULL (PyBUF_INDIRECT | PyBUF_WRITABLE | PyBUF_FORMAT)
103 #define PyBUF_FULL_RO (PyBUF_INDIRECT | PyBUF_FORMAT)
104 
105 
106 #define PyBUF_READ  0x100
107 #define PyBUF_WRITE 0x200
108 /* End buffer interface */
109 
110 
111 typedef struct {
112     /* Number implementations must check *both*
113        arguments for proper type and implement the necessary conversions
114        in the slot functions themselves. */
115 
116     binaryfunc nb_add;
117     binaryfunc nb_subtract;
118     binaryfunc nb_multiply;
119     binaryfunc nb_remainder;
120     binaryfunc nb_divmod;
121     ternaryfunc nb_power;
122     unaryfunc nb_negative;
123     unaryfunc nb_positive;
124     unaryfunc nb_absolute;
125     inquiry nb_bool;
126     unaryfunc nb_invert;
127     binaryfunc nb_lshift;
128     binaryfunc nb_rshift;
129     binaryfunc nb_and;
130     binaryfunc nb_xor;
131     binaryfunc nb_or;
132     unaryfunc nb_int;
133     void *nb_reserved;  /* the slot formerly known as nb_long */
134     unaryfunc nb_float;
135 
136     binaryfunc nb_inplace_add;
137     binaryfunc nb_inplace_subtract;
138     binaryfunc nb_inplace_multiply;
139     binaryfunc nb_inplace_remainder;
140     ternaryfunc nb_inplace_power;
141     binaryfunc nb_inplace_lshift;
142     binaryfunc nb_inplace_rshift;
143     binaryfunc nb_inplace_and;
144     binaryfunc nb_inplace_xor;
145     binaryfunc nb_inplace_or;
146 
147     binaryfunc nb_floor_divide;
148     binaryfunc nb_true_divide;
149     binaryfunc nb_inplace_floor_divide;
150     binaryfunc nb_inplace_true_divide;
151 
152     unaryfunc nb_index;
153 
154     binaryfunc nb_matrix_multiply;
155     binaryfunc nb_inplace_matrix_multiply;
156 } PyNumberMethods;
157 
158 typedef struct {
159     lenfunc sq_length;
160     binaryfunc sq_concat;
161     ssizeargfunc sq_repeat;
162     ssizeargfunc sq_item;
163     void *was_sq_slice;
164     ssizeobjargproc sq_ass_item;
165     void *was_sq_ass_slice;
166     objobjproc sq_contains;
167 
168     binaryfunc sq_inplace_concat;
169     ssizeargfunc sq_inplace_repeat;
170 } PySequenceMethods;
171 
172 typedef struct {
173     lenfunc mp_length;
174     binaryfunc mp_subscript;
175     objobjargproc mp_ass_subscript;
176 } PyMappingMethods;
177 
178 typedef struct {
179     unaryfunc am_await;
180     unaryfunc am_aiter;
181     unaryfunc am_anext;
182 } PyAsyncMethods;
183 
184 typedef struct {
185      getbufferproc bf_getbuffer;
186      releasebufferproc bf_releasebuffer;
187 } PyBufferProcs;
188 
189 /* Allow printfunc in the tp_vectorcall_offset slot for
190  * backwards-compatibility */
191 typedef Py_ssize_t printfunc;
192 
193 struct _typeobject {
194     PyObject_VAR_HEAD
195     const char *tp_name; /* For printing, in format "<module>.<name>" */
196     Py_ssize_t tp_basicsize, tp_itemsize; /* For allocation */
197 
198     /* Methods to implement standard operations */
199 
200     destructor tp_dealloc;
201     Py_ssize_t tp_vectorcall_offset;
202     getattrfunc tp_getattr;
203     setattrfunc tp_setattr;
204     PyAsyncMethods *tp_as_async; /* formerly known as tp_compare (Python 2)
205                                     or tp_reserved (Python 3) */
206     reprfunc tp_repr;
207 
208     /* Method suites for standard classes */
209 
210     PyNumberMethods *tp_as_number;
211     PySequenceMethods *tp_as_sequence;
212     PyMappingMethods *tp_as_mapping;
213 
214     /* More standard operations (here for binary compatibility) */
215 
216     hashfunc tp_hash;
217     ternaryfunc tp_call;
218     reprfunc tp_str;
219     getattrofunc tp_getattro;
220     setattrofunc tp_setattro;
221 
222     /* Functions to access object as input/output buffer */
223     PyBufferProcs *tp_as_buffer;
224 
225     /* Flags to define presence of optional/expanded features */
226     unsigned long tp_flags;
227 
228     const char *tp_doc; /* Documentation string */
229 
230     /* Assigned meaning in release 2.0 */
231     /* call function for all accessible objects */
232     traverseproc tp_traverse;
233 
234     /* delete references to contained objects */
235     inquiry tp_clear;
236 
237     /* Assigned meaning in release 2.1 */
238     /* rich comparisons */
239     richcmpfunc tp_richcompare;
240 
241     /* weak reference enabler */
242     Py_ssize_t tp_weaklistoffset;
243 
244     /* Iterators */
245     getiterfunc tp_iter;
246     iternextfunc tp_iternext;
247 
248     /* Attribute descriptor and subclassing stuff */
249     struct PyMethodDef *tp_methods;
250     struct PyMemberDef *tp_members;
251     struct PyGetSetDef *tp_getset;
252     struct _typeobject *tp_base;
253     PyObject *tp_dict;
254     descrgetfunc tp_descr_get;
255     descrsetfunc tp_descr_set;
256     Py_ssize_t tp_dictoffset;
257     initproc tp_init;
258     allocfunc tp_alloc;
259     newfunc tp_new;
260     freefunc tp_free; /* Low-level free-memory routine */
261     inquiry tp_is_gc; /* For PyObject_IS_GC */
262     PyObject *tp_bases;
263     PyObject *tp_mro; /* method resolution order */
264     PyObject *tp_cache;
265     PyObject *tp_subclasses;
266     PyObject *tp_weaklist;
267     destructor tp_del;
268 
269     /* Type attribute cache version tag. Added in version 2.6 */
270     unsigned int tp_version_tag;
271 
272     destructor tp_finalize;
273     vectorcallfunc tp_vectorcall;
274 };
275 
276 /* The *real* layout of a type object when allocated on the heap */
277 typedef struct _heaptypeobject {
278     /* Note: there's a dependency on the order of these members
279        in slotptr() in typeobject.c . */
280     PyTypeObject ht_type;
281     PyAsyncMethods as_async;
282     PyNumberMethods as_number;
283     PyMappingMethods as_mapping;
284     PySequenceMethods as_sequence; /* as_sequence comes after as_mapping,
285                                       so that the mapping wins when both
286                                       the mapping and the sequence define
287                                       a given operator (e.g. __getitem__).
288                                       see add_operators() in typeobject.c . */
289     PyBufferProcs as_buffer;
290     PyObject *ht_name, *ht_slots, *ht_qualname;
291     struct _dictkeysobject *ht_cached_keys;
292     PyObject *ht_module;
293     /* here are optional user slots, followed by the members. */
294 } PyHeapTypeObject;
295 
296 /* access macro to the members which are floating "behind" the object */
297 #define PyHeapType_GET_MEMBERS(etype) \
298     ((PyMemberDef *)(((char *)etype) + Py_TYPE(etype)->tp_basicsize))
299 
300 PyAPI_FUNC(const char *) _PyType_Name(PyTypeObject *);
301 PyAPI_FUNC(PyObject *) _PyType_Lookup(PyTypeObject *, PyObject *);
302 PyAPI_FUNC(PyObject *) _PyType_LookupId(PyTypeObject *, _Py_Identifier *);
303 PyAPI_FUNC(PyObject *) _PyObject_LookupSpecial(PyObject *, _Py_Identifier *);
304 PyAPI_FUNC(PyTypeObject *) _PyType_CalculateMetaclass(PyTypeObject *, PyObject *);
305 PyAPI_FUNC(PyObject *) _PyType_GetDocFromInternalDoc(const char *, const char *);
306 PyAPI_FUNC(PyObject *) _PyType_GetTextSignatureFromInternalDoc(const char *, const char *);
307 
308 struct _Py_Identifier;
309 PyAPI_FUNC(int) PyObject_Print(PyObject *, FILE *, int);
310 PyAPI_FUNC(void) _Py_BreakPoint(void);
311 PyAPI_FUNC(void) _PyObject_Dump(PyObject *);
312 PyAPI_FUNC(int) _PyObject_IsFreed(PyObject *);
313 
314 PyAPI_FUNC(int) _PyObject_IsAbstract(PyObject *);
315 PyAPI_FUNC(PyObject *) _PyObject_GetAttrId(PyObject *, struct _Py_Identifier *);
316 PyAPI_FUNC(int) _PyObject_SetAttrId(PyObject *, struct _Py_Identifier *, PyObject *);
317 PyAPI_FUNC(int) _PyObject_HasAttrId(PyObject *, struct _Py_Identifier *);
318 /* Replacements of PyObject_GetAttr() and _PyObject_GetAttrId() which
319    don't raise AttributeError.
320 
321    Return 1 and set *result != NULL if an attribute is found.
322    Return 0 and set *result == NULL if an attribute is not found;
323    an AttributeError is silenced.
324    Return -1 and set *result == NULL if an error other than AttributeError
325    is raised.
326 */
327 PyAPI_FUNC(int) _PyObject_LookupAttr(PyObject *, PyObject *, PyObject **);
328 PyAPI_FUNC(int) _PyObject_LookupAttrId(PyObject *, struct _Py_Identifier *, PyObject **);
329 
330 PyAPI_FUNC(int) _PyObject_GetMethod(PyObject *obj, PyObject *name, PyObject **method);
331 
332 PyAPI_FUNC(PyObject **) _PyObject_GetDictPtr(PyObject *);
333 PyAPI_FUNC(PyObject *) _PyObject_NextNotImplemented(PyObject *);
334 PyAPI_FUNC(void) PyObject_CallFinalizer(PyObject *);
335 PyAPI_FUNC(int) PyObject_CallFinalizerFromDealloc(PyObject *);
336 
337 /* Same as PyObject_Generic{Get,Set}Attr, but passing the attributes
338    dict as the last parameter. */
339 PyAPI_FUNC(PyObject *)
340 _PyObject_GenericGetAttrWithDict(PyObject *, PyObject *, PyObject *, int);
341 PyAPI_FUNC(int)
342 _PyObject_GenericSetAttrWithDict(PyObject *, PyObject *,
343                                  PyObject *, PyObject *);
344 
345 PyAPI_FUNC(PyObject *) _PyObject_FunctionStr(PyObject *);
346 
347 /* Safely decref `op` and set `op` to `op2`.
348  *
349  * As in case of Py_CLEAR "the obvious" code can be deadly:
350  *
351  *     Py_DECREF(op);
352  *     op = op2;
353  *
354  * The safe way is:
355  *
356  *      Py_SETREF(op, op2);
357  *
358  * That arranges to set `op` to `op2` _before_ decref'ing, so that any code
359  * triggered as a side-effect of `op` getting torn down no longer believes
360  * `op` points to a valid object.
361  *
362  * Py_XSETREF is a variant of Py_SETREF that uses Py_XDECREF instead of
363  * Py_DECREF.
364  */
365 
366 #define Py_SETREF(op, op2)                      \
367     do {                                        \
368         PyObject *_py_tmp = _PyObject_CAST(op); \
369         (op) = (op2);                           \
370         Py_DECREF(_py_tmp);                     \
371     } while (0)
372 
373 #define Py_XSETREF(op, op2)                     \
374     do {                                        \
375         PyObject *_py_tmp = _PyObject_CAST(op); \
376         (op) = (op2);                           \
377         Py_XDECREF(_py_tmp);                    \
378     } while (0)
379 
380 
381 PyAPI_DATA(PyTypeObject) _PyNone_Type;
382 PyAPI_DATA(PyTypeObject) _PyNotImplemented_Type;
383 
384 /* Maps Py_LT to Py_GT, ..., Py_GE to Py_LE.
385  * Defined in object.c.
386  */
387 PyAPI_DATA(int) _Py_SwappedOp[];
388 
389 PyAPI_FUNC(void)
390 _PyDebugAllocatorStats(FILE *out, const char *block_name, int num_blocks,
391                        size_t sizeof_block);
392 PyAPI_FUNC(void)
393 _PyObject_DebugTypeStats(FILE *out);
394 
395 /* Define a pair of assertion macros:
396    _PyObject_ASSERT_FROM(), _PyObject_ASSERT_WITH_MSG() and _PyObject_ASSERT().
397 
398    These work like the regular C assert(), in that they will abort the
399    process with a message on stderr if the given condition fails to hold,
400    but compile away to nothing if NDEBUG is defined.
401 
402    However, before aborting, Python will also try to call _PyObject_Dump() on
403    the given object.  This may be of use when investigating bugs in which a
404    particular object is corrupt (e.g. buggy a tp_visit method in an extension
405    module breaking the garbage collector), to help locate the broken objects.
406 
407    The WITH_MSG variant allows you to supply an additional message that Python
408    will attempt to print to stderr, after the object dump. */
409 #ifdef NDEBUG
410    /* No debugging: compile away the assertions: */
411 #  define _PyObject_ASSERT_FROM(obj, expr, msg, filename, lineno, func) \
412     ((void)0)
413 #else
414    /* With debugging: generate checks: */
415 #  define _PyObject_ASSERT_FROM(obj, expr, msg, filename, lineno, func) \
416     ((expr) \
417       ? (void)(0) \
418       : _PyObject_AssertFailed((obj), Py_STRINGIFY(expr), \
419                                (msg), (filename), (lineno), (func)))
420 #endif
421 
422 #define _PyObject_ASSERT_WITH_MSG(obj, expr, msg) \
423     _PyObject_ASSERT_FROM(obj, expr, msg, __FILE__, __LINE__, __func__)
424 #define _PyObject_ASSERT(obj, expr) \
425     _PyObject_ASSERT_WITH_MSG(obj, expr, NULL)
426 
427 #define _PyObject_ASSERT_FAILED_MSG(obj, msg) \
428     _PyObject_AssertFailed((obj), NULL, (msg), __FILE__, __LINE__, __func__)
429 
430 /* Declare and define _PyObject_AssertFailed() even when NDEBUG is defined,
431    to avoid causing compiler/linker errors when building extensions without
432    NDEBUG against a Python built with NDEBUG defined.
433 
434    msg, expr and function can be NULL. */
435 PyAPI_FUNC(void) _Py_NO_RETURN _PyObject_AssertFailed(
436     PyObject *obj,
437     const char *expr,
438     const char *msg,
439     const char *file,
440     int line,
441     const char *function);
442 
443 /* Check if an object is consistent. For example, ensure that the reference
444    counter is greater than or equal to 1, and ensure that ob_type is not NULL.
445 
446    Call _PyObject_AssertFailed() if the object is inconsistent.
447 
448    If check_content is zero, only check header fields: reduce the overhead.
449 
450    The function always return 1. The return value is just here to be able to
451    write:
452 
453    assert(_PyObject_CheckConsistency(obj, 1)); */
454 PyAPI_FUNC(int) _PyObject_CheckConsistency(
455     PyObject *op,
456     int check_content);
457 
458 
459 /* Trashcan mechanism, thanks to Christian Tismer.
460 
461 When deallocating a container object, it's possible to trigger an unbounded
462 chain of deallocations, as each Py_DECREF in turn drops the refcount on "the
463 next" object in the chain to 0.  This can easily lead to stack overflows,
464 especially in threads (which typically have less stack space to work with).
465 
466 A container object can avoid this by bracketing the body of its tp_dealloc
467 function with a pair of macros:
468 
469 static void
470 mytype_dealloc(mytype *p)
471 {
472     ... declarations go here ...
473 
474     PyObject_GC_UnTrack(p);        // must untrack first
475     Py_TRASHCAN_BEGIN(p, mytype_dealloc)
476     ... The body of the deallocator goes here, including all calls ...
477     ... to Py_DECREF on contained objects.                         ...
478     Py_TRASHCAN_END                // there should be no code after this
479 }
480 
481 CAUTION:  Never return from the middle of the body!  If the body needs to
482 "get out early", put a label immediately before the Py_TRASHCAN_END
483 call, and goto it.  Else the call-depth counter (see below) will stay
484 above 0 forever, and the trashcan will never get emptied.
485 
486 How it works:  The BEGIN macro increments a call-depth counter.  So long
487 as this counter is small, the body of the deallocator is run directly without
488 further ado.  But if the counter gets large, it instead adds p to a list of
489 objects to be deallocated later, skips the body of the deallocator, and
490 resumes execution after the END macro.  The tp_dealloc routine then returns
491 without deallocating anything (and so unbounded call-stack depth is avoided).
492 
493 When the call stack finishes unwinding again, code generated by the END macro
494 notices this, and calls another routine to deallocate all the objects that
495 may have been added to the list of deferred deallocations.  In effect, a
496 chain of N deallocations is broken into (N-1)/(PyTrash_UNWIND_LEVEL-1) pieces,
497 with the call stack never exceeding a depth of PyTrash_UNWIND_LEVEL.
498 
499 Since the tp_dealloc of a subclass typically calls the tp_dealloc of the base
500 class, we need to ensure that the trashcan is only triggered on the tp_dealloc
501 of the actual class being deallocated. Otherwise we might end up with a
502 partially-deallocated object. To check this, the tp_dealloc function must be
503 passed as second argument to Py_TRASHCAN_BEGIN().
504 */
505 
506 /* This is the old private API, invoked by the macros before 3.2.4.
507    Kept for binary compatibility of extensions using the stable ABI. */
508 PyAPI_FUNC(void) _PyTrash_deposit_object(PyObject*);
509 PyAPI_FUNC(void) _PyTrash_destroy_chain(void);
510 
511 /* This is the old private API, invoked by the macros before 3.9.
512    Kept for binary compatibility of extensions using the stable ABI. */
513 PyAPI_FUNC(void) _PyTrash_thread_deposit_object(PyObject*);
514 PyAPI_FUNC(void) _PyTrash_thread_destroy_chain(void);
515 
516 /* Forward declarations for PyThreadState */
517 struct _ts;
518 
519 /* Python 3.9 private API, invoked by the macros below. */
520 PyAPI_FUNC(int) _PyTrash_begin(struct _ts *tstate, PyObject *op);
521 PyAPI_FUNC(void) _PyTrash_end(struct _ts *tstate);
522 
523 #define PyTrash_UNWIND_LEVEL 50
524 
525 #define Py_TRASHCAN_BEGIN_CONDITION(op, cond) \
526     do { \
527         PyThreadState *_tstate = NULL; \
528         /* If "cond" is false, then _tstate remains NULL and the deallocator \
529          * is run normally without involving the trashcan */ \
530         if (cond) { \
531             _tstate = PyThreadState_GET(); \
532             if (_PyTrash_begin(_tstate, _PyObject_CAST(op))) { \
533                 break; \
534             } \
535         }
536         /* The body of the deallocator is here. */
537 #define Py_TRASHCAN_END \
538         if (_tstate) { \
539             _PyTrash_end(_tstate); \
540         } \
541     } while (0);
542 
543 #define Py_TRASHCAN_BEGIN(op, dealloc) \
544     Py_TRASHCAN_BEGIN_CONDITION(op, \
545         Py_TYPE(op)->tp_dealloc == (destructor)(dealloc))
546 
547 /* For backwards compatibility, these macros enable the trashcan
548  * unconditionally */
549 #define Py_TRASHCAN_SAFE_BEGIN(op) Py_TRASHCAN_BEGIN_CONDITION(op, 1)
550 #define Py_TRASHCAN_SAFE_END(op) Py_TRASHCAN_END
551 
552 #ifdef __cplusplus
553 }
554 #endif
555