1 /*
2 * atexit - allow programmer to define multiple exit functions to be executed
3 * upon normal program termination.
4 *
5 * Translated from atexit.py by Collin Winter.
6 + Copyright 2007 Python Software Foundation.
7 */
8
9 #include "Python.h"
10 #include "pycore_atexit.h"
11 #include "pycore_initconfig.h" // _PyStatus_NO_MEMORY
12 #include "pycore_interp.h" // PyInterpreterState.atexit
13 #include "pycore_pystate.h" // _PyInterpreterState_GET
14
15 /* ===================================================================== */
16 /* Callback machinery. */
17
18 static inline struct atexit_state*
19 get_atexit_state(void)
20 {
21 PyInterpreterState *interp = _PyInterpreterState_GET();
22 return &interp->atexit;
23 }
24
25
26 int
27 _Py_AtExit(PyInterpreterState *interp,
28 atexit_datacallbackfunc func, void *data)
29 {
30 assert(interp == _PyInterpreterState_GET());
31 atexit_callback *callback = PyMem_Malloc(sizeof(atexit_callback));
32 if (callback == NULL) {
33 PyErr_NoMemory();
34 return -1;
35 }
36 callback->func = func;
37 callback->data = data;
38 callback->next = NULL;
39
40 struct atexit_state *state = &interp->atexit;
41 if (state->ll_callbacks == NULL) {
42 state->ll_callbacks = callback;
43 state->last_ll_callback = callback;
44 }
45 else {
46 state->last_ll_callback->next = callback;
47 }
48 return 0;
49 }
50
51
52 static void
53 atexit_delete_cb(struct atexit_state *state, int i)
54 {
55 atexit_py_callback *cb = state->callbacks[i];
56 state->callbacks[i] = NULL;
57
58 Py_DECREF(cb->func);
59 Py_DECREF(cb->args);
60 Py_XDECREF(cb->kwargs);
61 PyMem_Free(cb);
62 }
63
64
65 /* Clear all callbacks without calling them */
66 static void
67 atexit_cleanup(struct atexit_state *state)
68 {
69 atexit_py_callback *cb;
70 for (int i = 0; i < state->ncallbacks; i++) {
71 cb = state->callbacks[i];
72 if (cb == NULL)
73 continue;
74
75 atexit_delete_cb(state, i);
76 }
77 state->ncallbacks = 0;
78 }
79
80
81 PyStatus
82 _PyAtExit_Init(PyInterpreterState *interp)
83 {
84 struct atexit_state *state = &interp->atexit;
85 // _PyAtExit_Init() must only be called once
86 assert(state->callbacks == NULL);
87
88 state->callback_len = 32;
89 state->ncallbacks = 0;
90 state->callbacks = PyMem_New(atexit_py_callback*, state->callback_len);
91 if (state->callbacks == NULL) {
92 return _PyStatus_NO_MEMORY();
93 }
94 return _PyStatus_OK();
95 }
96
97
98 void
99 _PyAtExit_Fini(PyInterpreterState *interp)
100 {
101 struct atexit_state *state = &interp->atexit;
102 atexit_cleanup(state);
103 PyMem_Free(state->callbacks);
104 state->callbacks = NULL;
105
106 atexit_callback *next = state->ll_callbacks;
107 state->ll_callbacks = NULL;
108 while (next != NULL) {
109 atexit_callback *callback = next;
110 next = callback->next;
111 atexit_datacallbackfunc exitfunc = callback->func;
112 void *data = callback->data;
113 // It was allocated in _PyAtExit_AddCallback().
114 PyMem_Free(callback);
115 exitfunc(data);
116 }
117 }
118
119
120 static void
121 atexit_callfuncs(struct atexit_state *state)
122 {
123 assert(!PyErr_Occurred());
124
125 if (state->ncallbacks == 0) {
126 return;
127 }
128
129 for (int i = state->ncallbacks - 1; i >= 0; i--) {
130 atexit_py_callback *cb = state->callbacks[i];
131 if (cb == NULL) {
132 continue;
133 }
134
135 // bpo-46025: Increment the refcount of cb->func as the call itself may unregister it
136 PyObject* the_func = Py_NewRef(cb->func);
137 PyObject *res = PyObject_Call(cb->func, cb->args, cb->kwargs);
138 if (res == NULL) {
139 _PyErr_WriteUnraisableMsg("in atexit callback", the_func);
140 }
141 else {
142 Py_DECREF(res);
143 }
144 Py_DECREF(the_func);
145 }
146
147 atexit_cleanup(state);
148
149 assert(!PyErr_Occurred());
150 }
151
152
153 void
154 _PyAtExit_Call(PyInterpreterState *interp)
155 {
156 struct atexit_state *state = &interp->atexit;
157 atexit_callfuncs(state);
158 }
159
160
161 /* ===================================================================== */
162 /* Module methods. */
163
164
165 PyDoc_STRVAR(atexit_register__doc__,
166 "register(func, *args, **kwargs) -> func\n\
167 \n\
168 Register a function to be executed upon normal program termination\n\
169 \n\
170 func - function to be called at exit\n\
171 args - optional arguments to pass to func\n\
172 kwargs - optional keyword arguments to pass to func\n\
173 \n\
174 func is returned to facilitate usage as a decorator.");
175
176 static PyObject *
177 atexit_register(PyObject *module, PyObject *args, PyObject *kwargs)
178 {
179 if (PyTuple_GET_SIZE(args) == 0) {
180 PyErr_SetString(PyExc_TypeError,
181 "register() takes at least 1 argument (0 given)");
182 return NULL;
183 }
184
185 PyObject *func = PyTuple_GET_ITEM(args, 0);
186 if (!PyCallable_Check(func)) {
187 PyErr_SetString(PyExc_TypeError,
188 "the first argument must be callable");
189 return NULL;
190 }
191
192 struct atexit_state *state = get_atexit_state();
193 if (state->ncallbacks >= state->callback_len) {
194 atexit_py_callback **r;
195 state->callback_len += 16;
196 size_t size = sizeof(atexit_py_callback*) * (size_t)state->callback_len;
197 r = (atexit_py_callback**)PyMem_Realloc(state->callbacks, size);
198 if (r == NULL) {
199 return PyErr_NoMemory();
200 }
201 state->callbacks = r;
202 }
203
204 atexit_py_callback *callback = PyMem_Malloc(sizeof(atexit_py_callback));
205 if (callback == NULL) {
206 return PyErr_NoMemory();
207 }
208
209 callback->args = PyTuple_GetSlice(args, 1, PyTuple_GET_SIZE(args));
210 if (callback->args == NULL) {
211 PyMem_Free(callback);
212 return NULL;
213 }
214 callback->func = Py_NewRef(func);
215 callback->kwargs = Py_XNewRef(kwargs);
216
217 state->callbacks[state->ncallbacks++] = callback;
218
219 return Py_NewRef(func);
220 }
221
222 PyDoc_STRVAR(atexit_run_exitfuncs__doc__,
223 "_run_exitfuncs() -> None\n\
224 \n\
225 Run all registered exit functions.\n\
226 \n\
227 If a callback raises an exception, it is logged with sys.unraisablehook.");
228
229 static PyObject *
230 atexit_run_exitfuncs(PyObject *module, PyObject *unused)
231 {
232 struct atexit_state *state = get_atexit_state();
233 atexit_callfuncs(state);
234 Py_RETURN_NONE;
235 }
236
237 PyDoc_STRVAR(atexit_clear__doc__,
238 "_clear() -> None\n\
239 \n\
240 Clear the list of previously registered exit functions.");
241
242 static PyObject *
243 atexit_clear(PyObject *module, PyObject *unused)
244 {
245 atexit_cleanup(get_atexit_state());
246 Py_RETURN_NONE;
247 }
248
249 PyDoc_STRVAR(atexit_ncallbacks__doc__,
250 "_ncallbacks() -> int\n\
251 \n\
252 Return the number of registered exit functions.");
253
254 static PyObject *
255 atexit_ncallbacks(PyObject *module, PyObject *unused)
256 {
257 struct atexit_state *state = get_atexit_state();
258 return PyLong_FromSsize_t(state->ncallbacks);
259 }
260
261 PyDoc_STRVAR(atexit_unregister__doc__,
262 "unregister(func) -> None\n\
263 \n\
264 Unregister an exit function which was previously registered using\n\
265 atexit.register\n\
266 \n\
267 func - function to be unregistered");
268
269 static PyObject *
270 atexit_unregister(PyObject *module, PyObject *func)
271 {
272 struct atexit_state *state = get_atexit_state();
273 for (int i = 0; i < state->ncallbacks; i++)
274 {
275 atexit_py_callback *cb = state->callbacks[i];
276 if (cb == NULL) {
277 continue;
278 }
279
280 int eq = PyObject_RichCompareBool(cb->func, func, Py_EQ);
281 if (eq < 0) {
282 return NULL;
283 }
284 if (eq) {
285 atexit_delete_cb(state, i);
286 }
287 }
288 Py_RETURN_NONE;
289 }
290
291
292 static PyMethodDef atexit_methods[] = {
293 {"register", _PyCFunction_CAST(atexit_register), METH_VARARGS|METH_KEYWORDS,
294 atexit_register__doc__},
295 {"_clear", (PyCFunction) atexit_clear, METH_NOARGS,
296 atexit_clear__doc__},
297 {"unregister", (PyCFunction) atexit_unregister, METH_O,
298 atexit_unregister__doc__},
299 {"_run_exitfuncs", (PyCFunction) atexit_run_exitfuncs, METH_NOARGS,
300 atexit_run_exitfuncs__doc__},
301 {"_ncallbacks", (PyCFunction) atexit_ncallbacks, METH_NOARGS,
302 atexit_ncallbacks__doc__},
303 {NULL, NULL} /* sentinel */
304 };
305
306
307 /* ===================================================================== */
308 /* Initialization function. */
309
310 PyDoc_STRVAR(atexit__doc__,
311 "allow programmer to define multiple exit functions to be executed\n\
312 upon normal program termination.\n\
313 \n\
314 Two public functions, register and unregister, are defined.\n\
315 ");
316
317 static PyModuleDef_Slot atexitmodule_slots[] = {
318 {Py_mod_multiple_interpreters, Py_MOD_PER_INTERPRETER_GIL_SUPPORTED},
319 {0, NULL}
320 };
321
322 static struct PyModuleDef atexitmodule = {
323 PyModuleDef_HEAD_INIT,
324 .m_name = "atexit",
325 .m_doc = atexit__doc__,
326 .m_size = 0,
327 .m_methods = atexit_methods,
328 .m_slots = atexitmodule_slots,
329 };
330
331 PyMODINIT_FUNC
332 PyInit_atexit(void)
333 {
334 return PyModuleDef_Init(&atexitmodule);
335 }