https://github.com/python/cpython/commit/afec2c70eb5828b9af32f36e743a1ce6f90d1711
commit: afec2c70eb5828b9af32f36e743a1ce6f90d1711
branch: 3.13
author: Bénédikt Tran <[email protected]>
committer: picnixz <[email protected]>
date: 2025-09-06T12:17:57+02:00
summary:
[3.13] gh-116946: fully implement GC protocol for `_curses_panel.panel`
(GH-138333) (#138428)
[3.14] gh-116946: fully implement GC protocol for `_curses_panel.panel`
(GH-138333)
This commit fixes possible reference loops via `panel.set_userptr`
by implementing `tp_clear` and `tp_traverse` for panel objects.
(cherry picked from commit 572df47840d910b9fc9cd951074232ae89442be1)
files:
M Modules/_curses_panel.c
diff --git a/Modules/_curses_panel.c b/Modules/_curses_panel.c
index bbbb62c9066df0..7241c3d70a772d 100644
--- a/Modules/_curses_panel.c
+++ b/Modules/_curses_panel.c
@@ -32,6 +32,8 @@ typedef struct {
PyTypeObject *PyCursesPanel_Type;
} _curses_panel_state;
+typedef struct PyCursesPanelObject PyCursesPanelObject;
+
static inline _curses_panel_state *
get_curses_panel_state(PyObject *module)
{
@@ -40,6 +42,25 @@ get_curses_panel_state(PyObject *module)
return (_curses_panel_state *)state;
}
+static inline _curses_panel_state *
+get_curses_panel_state_by_panel(PyCursesPanelObject *panel)
+{
+ /*
+ * Note: 'state' may be NULL if Py_TYPE(panel) is not a heap
+ * type associated with this module, but the compiler would
+ * have likely already complained with an "invalid pointer
+ * type" at compile-time.
+ *
+ * To make it more robust, all functions recovering a module's
+ * state from an object should expect to return NULL with an
+ * exception set (in contrast to functions recovering a module's
+ * state from a module itself).
+ */
+ void *state = PyType_GetModuleState(Py_TYPE(panel));
+ assert(state != NULL);
+ return (_curses_panel_state *)state;
+}
+
static int
_curses_panel_clear(PyObject *mod)
{
@@ -95,12 +116,14 @@ PyCursesCheckERR(_curses_panel_state *state, int code,
const char *fname)
/* Definition of the panel object and panel type */
-typedef struct {
+typedef struct PyCursesPanelObject {
PyObject_HEAD
PANEL *pan;
PyCursesWindowObject *wo; /* for reference counts */
} PyCursesPanelObject;
+#define _PyCursesPanelObject_CAST(op) ((PyCursesPanelObject *)(op))
+
/* Some helper functions. The problem is that there's always a window
associated with a panel. To ensure that Python's GC doesn't pull
this window from under our feet we need to keep track of references
@@ -260,8 +283,11 @@ static PyObject *
PyCursesPanel_New(_curses_panel_state *state, PANEL *pan,
PyCursesWindowObject *wo)
{
- PyCursesPanelObject *po = PyObject_New(PyCursesPanelObject,
- state->PyCursesPanel_Type);
+ assert(state != NULL);
+ PyTypeObject *type = state->PyCursesPanel_Type;
+ assert(type != NULL);
+ assert(type->tp_alloc != NULL);
+ PyCursesPanelObject *po = (PyCursesPanelObject *)type->tp_alloc(type, 0);
if (po == NULL) {
return NULL;
}
@@ -276,26 +302,57 @@ PyCursesPanel_New(_curses_panel_state *state, PANEL *pan,
return (PyObject *)po;
}
+static int
+PyCursesPanel_Clear(PyObject *op)
+{
+ PyCursesPanelObject *self = _PyCursesPanelObject_CAST(op);
+ PyObject *extra = (PyObject *)panel_userptr(self->pan);
+ if (extra != NULL) {
+ Py_DECREF(extra);
+ if (set_panel_userptr(self->pan, NULL) == ERR) {
+ _curses_panel_state *state = get_curses_panel_state_by_panel(self);
+ PyErr_SetString(state->PyCursesError,
+ "set_panel_userptr() returned ERR");
+ return -1;
+ }
+ }
+ // self->wo should not be cleared because an associated WINDOW may exist
+ return 0;
+}
+
static void
-PyCursesPanel_Dealloc(PyCursesPanelObject *po)
+PyCursesPanel_Dealloc(PyObject *self)
{
- PyObject *tp, *obj;
+ PyTypeObject *tp = Py_TYPE(self);
+ PyObject_GC_UnTrack(self);
- tp = (PyObject *) Py_TYPE(po);
- obj = (PyObject *) panel_userptr(po->pan);
- if (obj) {
- (void)set_panel_userptr(po->pan, NULL);
- Py_DECREF(obj);
+ PyCursesPanelObject *po = _PyCursesPanelObject_CAST(self);
+ if (PyCursesPanel_Clear(self) < 0) {
+ PyErr_FormatUnraisable("Exception ignored in PyCursesPanel_Dealloc()");
+ }
+ if (del_panel(po->pan) == ERR && !PyErr_Occurred()) {
+ _curses_panel_state *state = get_curses_panel_state_by_panel(po);
+ PyErr_SetString(state->PyCursesError, "del_panel() returned ERR");
+ PyErr_FormatUnraisable("Exception ignored in PyCursesPanel_Dealloc()");
}
- (void)del_panel(po->pan);
if (po->wo != NULL) {
Py_DECREF(po->wo);
remove_lop(po);
}
- PyObject_Free(po);
+ tp->tp_free(po);
Py_DECREF(tp);
}
+static int
+PyCursesPanel_Traverse(PyObject *op, visitproc visit, void *arg)
+{
+ PyCursesPanelObject *self = _PyCursesPanelObject_CAST(op);
+ Py_VISIT(Py_TYPE(op));
+ Py_VISIT(panel_userptr(self->pan));
+ Py_VISIT(self->wo);
+ return 0;
+}
+
/* panel_above(NULL) returns the bottom panel in the stack. To get
this behaviour we use curses.panel.bottom_panel(). */
/*[clinic input]
@@ -517,7 +574,9 @@ static PyMethodDef PyCursesPanel_Methods[] = {
/* -------------------------------------------------------*/
static PyType_Slot PyCursesPanel_Type_slots[] = {
+ {Py_tp_clear, PyCursesPanel_Clear},
{Py_tp_dealloc, PyCursesPanel_Dealloc},
+ {Py_tp_traverse, PyCursesPanel_Traverse},
{Py_tp_methods, PyCursesPanel_Methods},
{0, 0},
};
@@ -525,7 +584,11 @@ static PyType_Slot PyCursesPanel_Type_slots[] = {
static PyType_Spec PyCursesPanel_Type_spec = {
.name = "_curses_panel.panel",
.basicsize = sizeof(PyCursesPanelObject),
- .flags = Py_TPFLAGS_DEFAULT | Py_TPFLAGS_DISALLOW_INSTANTIATION,
+ .flags = (
+ Py_TPFLAGS_DEFAULT
+ | Py_TPFLAGS_DISALLOW_INSTANTIATION
+ | Py_TPFLAGS_HAVE_GC
+ ),
.slots = PyCursesPanel_Type_slots
};
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