[Python-checkins] gh-99537: Use Py_SETREF() function in C code (#99657)

vstinner webhook-mailer at python.org
Tue Nov 22 07:39:17 EST 2022

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---

https://github.com/python/cpython/commit/135ec7cefbaffd516b77362ad2b2ad1025af462e
commit: 135ec7cefbaffd516b77362ad2b2ad1025af462e
branch: main
author: Victor Stinner <vstinner at python.org>
committer: vstinner <vstinner at python.org>
date: 2022年11月22日T13:39:11+01:00
summary:
gh-99537: Use Py_SETREF() function in C code (#99657)
Fix potential race condition in code patterns:
* Replace "Py_DECREF(var); var = new;" with "Py_SETREF(var, new);"
* Replace "Py_XDECREF(var); var = new;" with "Py_XSETREF(var, new);"
* Replace "Py_CLEAR(var); var = new;" with "Py_XSETREF(var, new);"
Other changes:
* Replace "old = var; var = new; Py_DECREF(var)"
 with "Py_SETREF(var, new);"
* Replace "old = var; var = new; Py_XDECREF(var)"
 with "Py_XSETREF(var, new);"
* And remove the "old" variable.
files:
M Objects/bytesobject.c
M Objects/capsule.c
M Objects/fileobject.c
M Objects/floatobject.c
M Objects/genobject.c
M Objects/setobject.c
M Objects/sliceobject.c
M Objects/stringlib/unicode_format.h
M Objects/typeobject.c
M Objects/unicodeobject.c
M Objects/weakrefobject.c
M Python/_warnings.c
M Python/bltinmodule.c
M Python/compile.c
M Python/errors.c
M Python/hamt.c
M Python/pythonrun.c
M Python/sysmodule.c
M Python/traceback.c
diff --git a/Objects/bytesobject.c b/Objects/bytesobject.c
index 91c89bbd9005..a63f396e022f 100644
--- a/Objects/bytesobject.c
+++ b/Objects/bytesobject.c
@@ -2109,9 +2109,7 @@ bytes_translate_impl(PyBytesObject *self, PyObject *table,
 changed = 1;
 }
 if (!changed && PyBytes_CheckExact(input_obj)) {
- Py_INCREF(input_obj);
- Py_DECREF(result);
- result = input_obj;
+ Py_SETREF(result, Py_NewRef(input_obj));
 }
 PyBuffer_Release(&del_table_view);
 PyBuffer_Release(&table_view);
diff --git a/Objects/capsule.c b/Objects/capsule.c
index 606e50e69611..baaddb3f1f08 100644
--- a/Objects/capsule.c
+++ b/Objects/capsule.c
@@ -220,8 +220,7 @@ PyCapsule_Import(const char *name, int no_block)
 }
 } else {
 PyObject *object2 = PyObject_GetAttrString(object, trace);
- Py_DECREF(object);
- object = object2;
+ Py_SETREF(object, object2);
 }
 if (!object) {
 goto EXIT;
diff --git a/Objects/fileobject.c b/Objects/fileobject.c
index ab67cd23cef3..bf56be5f7ea7 100644
--- a/Objects/fileobject.c
+++ b/Objects/fileobject.c
@@ -88,8 +88,7 @@ PyFile_GetLine(PyObject *f, int n)
 else {
 PyObject *v;
 v = PyBytes_FromStringAndSize(s, len-1);
- Py_DECREF(result);
- result = v;
+ Py_SETREF(result, v);
 }
 }
 }
@@ -104,8 +103,7 @@ PyFile_GetLine(PyObject *f, int n)
 else if (PyUnicode_READ_CHAR(result, len-1) == '\n') {
 PyObject *v;
 v = PyUnicode_Substring(result, 0, len-1);
- Py_DECREF(result);
- result = v;
+ Py_SETREF(result, v);
 }
 }
 return result;
diff --git a/Objects/floatobject.c b/Objects/floatobject.c
index 46016e946ad3..912b742f797d 100644
--- a/Objects/floatobject.c
+++ b/Objects/floatobject.c
@@ -531,20 +531,17 @@ float_richcompare(PyObject *v, PyObject *w, int op)
 temp = _PyLong_Lshift(ww, 1);
 if (temp == NULL)
 goto Error;
- Py_DECREF(ww);
- ww = temp;
+ Py_SETREF(ww, temp);
 
 temp = _PyLong_Lshift(vv, 1);
 if (temp == NULL)
 goto Error;
- Py_DECREF(vv);
- vv = temp;
+ Py_SETREF(vv, temp);
 
 temp = PyNumber_Or(vv, _PyLong_GetOne());
 if (temp == NULL)
 goto Error;
- Py_DECREF(vv);
- vv = temp;
+ Py_SETREF(vv, temp);
 }
 
 r = PyObject_RichCompareBool(vv, ww, op);
diff --git a/Objects/genobject.c b/Objects/genobject.c
index 6661e3fb9461..c006f1af2177 100644
--- a/Objects/genobject.c
+++ b/Objects/genobject.c
@@ -491,8 +491,7 @@ _gen_throw(PyGenObject *gen, int close_on_genexit,
 }
 else {
 /* Normalize to raise <class>, <instance> */
- Py_XDECREF(val);
- val = typ;
+ Py_XSETREF(val, typ);
 typ = Py_NewRef(PyExceptionInstance_Class(typ));
 
 if (tb == NULL)
diff --git a/Objects/setobject.c b/Objects/setobject.c
index e0646768384a..ae9e9b994461 100644
--- a/Objects/setobject.c
+++ b/Objects/setobject.c
@@ -1270,8 +1270,7 @@ set_intersection_multi(PySetObject *so, PyObject *args)
 Py_DECREF(result);
 return NULL;
 }
- Py_DECREF(result);
- result = newresult;
+ Py_SETREF(result, newresult);
 }
 return result;
 }
diff --git a/Objects/sliceobject.c b/Objects/sliceobject.c
index 1da1df309072..5694bd9c661f 100644
--- a/Objects/sliceobject.c
+++ b/Objects/sliceobject.c
@@ -448,8 +448,7 @@ _PySlice_GetLongIndices(PySliceObject *self, PyObject *length,
 if (_PyLong_Sign(start) < 0) {
 /* start += length */
 PyObject *tmp = PyNumber_Add(start, length);
- Py_DECREF(start);
- start = tmp;
+ Py_SETREF(start, tmp);
 if (start == NULL)
 goto error;
 
@@ -457,9 +456,7 @@ _PySlice_GetLongIndices(PySliceObject *self, PyObject *length,
 if (cmp_result < 0)
 goto error;
 if (cmp_result) {
- Py_INCREF(lower);
- Py_DECREF(start);
- start = lower;
+ Py_SETREF(start, Py_NewRef(lower));
 }
 }
 else {
@@ -467,9 +464,7 @@ _PySlice_GetLongIndices(PySliceObject *self, PyObject *length,
 if (cmp_result < 0)
 goto error;
 if (cmp_result) {
- Py_INCREF(upper);
- Py_DECREF(start);
- start = upper;
+ Py_SETREF(start, Py_NewRef(upper));
 }
 }
 }
@@ -486,8 +481,7 @@ _PySlice_GetLongIndices(PySliceObject *self, PyObject *length,
 if (_PyLong_Sign(stop) < 0) {
 /* stop += length */
 PyObject *tmp = PyNumber_Add(stop, length);
- Py_DECREF(stop);
- stop = tmp;
+ Py_SETREF(stop, tmp);
 if (stop == NULL)
 goto error;
 
@@ -495,9 +489,7 @@ _PySlice_GetLongIndices(PySliceObject *self, PyObject *length,
 if (cmp_result < 0)
 goto error;
 if (cmp_result) {
- Py_INCREF(lower);
- Py_DECREF(stop);
- stop = lower;
+ Py_SETREF(stop, Py_NewRef(lower));
 }
 }
 else {
@@ -505,9 +497,7 @@ _PySlice_GetLongIndices(PySliceObject *self, PyObject *length,
 if (cmp_result < 0)
 goto error;
 if (cmp_result) {
- Py_INCREF(upper);
- Py_DECREF(stop);
- stop = upper;
+ Py_SETREF(stop, Py_NewRef(upper));
 }
 }
 }
diff --git a/Objects/stringlib/unicode_format.h b/Objects/stringlib/unicode_format.h
index e970588a7e34..ccd7c77c0a03 100644
--- a/Objects/stringlib/unicode_format.h
+++ b/Objects/stringlib/unicode_format.h
@@ -473,8 +473,7 @@ get_field_object(SubString *input, PyObject *args, PyObject *kwargs,
 goto error;
 
 /* assign to obj */
- Py_DECREF(obj);
- obj = tmp;
+ Py_SETREF(obj, tmp);
 }
 /* end of iterator, this is the non-error case */
 if (ok == 1)
@@ -825,8 +824,7 @@ output_markup(SubString *field_name, SubString *format_spec,
 goto done;
 
 /* do the assignment, transferring ownership: fieldobj = tmp */
- Py_DECREF(fieldobj);
- fieldobj = tmp;
+ Py_SETREF(fieldobj, tmp);
 tmp = NULL;
 }
 
diff --git a/Objects/typeobject.c b/Objects/typeobject.c
index 9d868d51f027..312406993c5b 100644
--- a/Objects/typeobject.c
+++ b/Objects/typeobject.c
@@ -5968,8 +5968,7 @@ object___dir___impl(PyObject *self)
 else {
 /* Copy __dict__ to avoid mutating it. */
 PyObject *temp = PyDict_Copy(dict);
- Py_DECREF(dict);
- dict = temp;
+ Py_SETREF(dict, temp);
 }
 
 if (dict == NULL)
@@ -9377,8 +9376,7 @@ super_getattro(PyObject *self, PyObject *name)
 (See SF ID #743627) */
 (su->obj == (PyObject *)starttype) ? NULL : su->obj,
 (PyObject *)starttype);
- Py_DECREF(res);
- res = res2;
+ Py_SETREF(res, res2);
 }
 
 Py_DECREF(mro);
diff --git a/Objects/unicodeobject.c b/Objects/unicodeobject.c
index b1acfc71379c..55f029dd504c 100644
--- a/Objects/unicodeobject.c
+++ b/Objects/unicodeobject.c
@@ -13572,8 +13572,7 @@ _PyUnicode_FormatLong(PyObject *val, int alt, int prec, int type)
 for (i = 0; i < numdigits; i++)
 *b1++ = *buf++;
 *b1 = '0円';
- Py_DECREF(result);
- result = r1;
+ Py_SETREF(result, r1);
 buf = PyBytes_AS_STRING(result);
 len = numnondigits + prec;
 }
@@ -13590,8 +13589,7 @@ _PyUnicode_FormatLong(PyObject *val, int alt, int prec, int type)
 || buf != PyUnicode_DATA(result)) {
 PyObject *unicode;
 unicode = _PyUnicode_FromASCII(buf, len);
- Py_DECREF(result);
- result = unicode;
+ Py_SETREF(result, unicode);
 }
 else if (len != PyUnicode_GET_LENGTH(result)) {
 if (PyUnicode_Resize(&result, len) < 0)
diff --git a/Objects/weakrefobject.c b/Objects/weakrefobject.c
index ff284c882b0f..bd7720e27533 100644
--- a/Objects/weakrefobject.c
+++ b/Objects/weakrefobject.c
@@ -824,8 +824,7 @@ PyWeakref_NewRef(PyObject *ob, PyObject *callback)
 during GC. Return that one instead of this one
 to avoid violating the invariants of the list
 of weakrefs for ob. */
- Py_DECREF(result);
- result = (PyWeakReference*)Py_NewRef(ref);
+ Py_SETREF(result, (PyWeakReference*)Py_NewRef(ref));
 }
 }
 else {
@@ -888,8 +887,7 @@ PyWeakref_NewProxy(PyObject *ob, PyObject *callback)
 during GC. Return that one instead of this one
 to avoid violating the invariants of the list
 of weakrefs for ob. */
- Py_DECREF(result);
- result = (PyWeakReference*)Py_NewRef(proxy);
+ Py_SETREF(result, (PyWeakReference*)Py_NewRef(proxy));
 goto skip_insert;
 }
 prev = ref;
diff --git a/Python/_warnings.c b/Python/_warnings.c
index d703e1e6d843..046c37eb49ba 100644
--- a/Python/_warnings.c
+++ b/Python/_warnings.c
@@ -801,8 +801,7 @@ next_external_frame(PyFrameObject *frame)
 {
 do {
 PyFrameObject *back = PyFrame_GetBack(frame);
- Py_DECREF(frame);
- frame = back;
+ Py_SETREF(frame, back);
 } while (frame != NULL && is_internal_frame(frame));
 
 return frame;
@@ -828,8 +827,7 @@ setup_context(Py_ssize_t stack_level, PyObject **filename, int *lineno,
 if (stack_level <= 0 || is_internal_frame(f)) {
 while (--stack_level > 0 && f != NULL) {
 PyFrameObject *back = PyFrame_GetBack(f);
- Py_DECREF(f);
- f = back;
+ Py_SETREF(f, back);
 }
 }
 else {
diff --git a/Python/bltinmodule.c b/Python/bltinmodule.c
index 119e21ae0da2..c2cf79a727f0 100644
--- a/Python/bltinmodule.c
+++ b/Python/bltinmodule.c
@@ -168,8 +168,7 @@ builtin___build_class__(PyObject *self, PyObject *const *args, Py_ssize_t nargs,
 goto error;
 }
 if (winner != meta) {
- Py_DECREF(meta);
- meta = Py_NewRef(winner);
+ Py_SETREF(meta, Py_NewRef(winner));
 }
 }
 /* else: meta is not a class, so we cannot do the metaclass
diff --git a/Python/compile.c b/Python/compile.c
index 9226bc233ead..366321143a54 100644
--- a/Python/compile.c
+++ b/Python/compile.c
@@ -8280,9 +8280,7 @@ merge_const_one(PyObject *const_cache, PyObject **obj)
 t = PyTuple_GET_ITEM(t, 1);
 }
 
- Py_INCREF(t);
- Py_DECREF(*obj);
- *obj = t;
+ Py_SETREF(*obj, Py_NewRef(t));
 return 1;
 }
 
diff --git a/Python/errors.c b/Python/errors.c
index d74ac347484f..6a42f5912f94 100644
--- a/Python/errors.c
+++ b/Python/errors.c
@@ -353,16 +353,13 @@ _PyErr_NormalizeException(PyThreadState *tstate, PyObject **exc,
 if (fixed_value == NULL) {
 goto error;
 }
- Py_DECREF(value);
- value = fixed_value;
+ Py_SETREF(value, fixed_value);
 }
 /* If the class of the instance doesn't exactly match the
 class of the type, believe the instance.
 */
 else if (inclass != type) {
- Py_INCREF(inclass);
- Py_DECREF(type);
- type = inclass;
+ Py_SETREF(type, Py_NewRef(inclass));
 }
 }
 *exc = type;
diff --git a/Python/hamt.c b/Python/hamt.c
index c4e47eb9e570..8cb94641bef2 100644
--- a/Python/hamt.c
+++ b/Python/hamt.c
@@ -1354,8 +1354,7 @@ hamt_node_collision_assoc(PyHamtNode_Collision *self,
 }
 
 /* Replace the old value with the new value for the our key. */
- Py_DECREF(new_node->c_array[val_idx]);
- new_node->c_array[val_idx] = Py_NewRef(val);
+ Py_SETREF(new_node->c_array[val_idx], Py_NewRef(val));
 
 return (PyHamtNode *)new_node;
 
diff --git a/Python/pythonrun.c b/Python/pythonrun.c
index 70872222eb64..35292b6478a8 100644
--- a/Python/pythonrun.c
+++ b/Python/pythonrun.c
@@ -718,8 +718,7 @@ _Py_HandleSystemExit(int *exitcode_p)
 /* The error code should be in the `code' attribute. */
 PyObject *code = PyObject_GetAttr(value, &_Py_ID(code));
 if (code) {
- Py_DECREF(value);
- value = code;
+ Py_SETREF(value, code);
 if (value == Py_None)
 goto done;
 }
diff --git a/Python/sysmodule.c b/Python/sysmodule.c
index 6f0a126a6227..88f806e616f2 100644
--- a/Python/sysmodule.c
+++ b/Python/sysmodule.c
@@ -198,8 +198,7 @@ sys_audit_tstate(PyThreadState *ts, const char *event,
 eventArgs = _Py_VaBuildValue_SizeT(argFormat, vargs);
 if (eventArgs && !PyTuple_Check(eventArgs)) {
 PyObject *argTuple = PyTuple_Pack(1, eventArgs);
- Py_DECREF(eventArgs);
- eventArgs = argTuple;
+ Py_SETREF(eventArgs, argTuple);
 }
 }
 else {
diff --git a/Python/traceback.c b/Python/traceback.c
index 356e64364832..da26c9b260a3 100644
--- a/Python/traceback.c
+++ b/Python/traceback.c
@@ -136,9 +136,7 @@ tb_next_set(PyTracebackObject *self, PyObject *new_next, void *Py_UNUSED(_))
 cursor = cursor->tb_next;
 }
 
- PyObject *old_next = (PyObject*)self->tb_next;
- self->tb_next = (PyTracebackObject *)Py_XNewRef(new_next);
- Py_XDECREF(old_next);
+ Py_XSETREF(self->tb_next, (PyTracebackObject *)Py_XNewRef(new_next));
 
 return 0;
 }
@@ -533,8 +531,7 @@ display_source_line_with_margin(PyObject *f, PyObject *filename, int lineno, int
 PyObject *truncated;
 truncated = PyUnicode_Substring(lineobj, i, PyUnicode_GET_LENGTH(lineobj));
 if (truncated) {
- Py_DECREF(lineobj);
- lineobj = truncated;
+ Py_SETREF(lineobj, truncated);
 } else {
 PyErr_Clear();
 }

---

• Previous message (by thread): [Python-checkins] gh-91053: Add an optional callback that is invoked whenever a function is modified (#98175)
• Next message (by thread): [Python-checkins] gh-99537: Use Py_SETREF() function in C code (#99656)
• Messages sorted by: [ date ] [ thread ] [ subject ] [ author ]

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