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[3.12] gh-118272: Clear generator frame's locals when the generator is closed #118451

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Merged
merged 2 commits into from
May 2, 2024
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[3.12] gh-118272: Clear generator frame's locals when the generator is closed #118451

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f3515ca
gh-118272: Clear generator frame's locals when the generator is closed
iritkatriel Apr 30, 2024
3dc25ae
set stacktop to 0 before decref
iritkatriel May 1, 2024
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3 changes: 3 additions & 0 deletions Include/internal/pycore_frame.h
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Original file line number Diff line number Diff line change
Expand Up @@ -213,6 +213,9 @@ _PyFrame_GetFrameObject(_PyInterpreterFrame *frame)
return _PyFrame_MakeAndSetFrameObject(frame);
}

void
_PyFrame_ClearLocals(_PyInterpreterFrame *frame);

/* Clears all references in the frame.
* If take is non-zero, then the _PyInterpreterFrame frame
* may be transferred to the frame object it references
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20 changes: 20 additions & 0 deletions Lib/test/test_generators.py
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Expand Up @@ -450,6 +450,26 @@ def g():
self.assertIsInstance(cm.exception.value, StopIteration)
self.assertEqual(cm.exception.value.value, 2)

def test_close_releases_frame_locals(self):
# See gh-118272

class Foo:
pass

f = Foo()
f_wr = weakref.ref(f)

def genfn():
a = f
yield

g = genfn()
next(g)
del f
g.close()
support.gc_collect()
self.assertIsNone(f_wr())


class GeneratorThrowTest(unittest.TestCase):

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2 changes: 2 additions & 0 deletions Misc/NEWS.d/next/Core and Builtins/2024-04-30-23-06-10.gh-issue-118272.5ptjk_.rst
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@@ -0,0 +1,2 @@
Fix bug where ``generator.close`` does not free the generator frame's
locals.
1 change: 1 addition & 0 deletions Objects/genobject.c
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Expand Up @@ -403,6 +403,7 @@ gen_close(PyGenObject *gen, PyObject *args)
* StopIteration. */
if (exception_handler_depth == 1) {
gen->gi_frame_state = FRAME_COMPLETED;
_PyFrame_ClearLocals((_PyInterpreterFrame *)gen->gi_iframe);
Py_RETURN_NONE;
}
}
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18 changes: 13 additions & 5 deletions Python/frame.c
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Expand Up @@ -115,6 +115,18 @@ take_ownership(PyFrameObject *f, _PyInterpreterFrame *frame)
}
}

void
_PyFrame_ClearLocals(_PyInterpreterFrame *frame)
{
assert(frame->stacktop >= 0);
int stacktop = frame->stacktop;
frame->stacktop = 0;
for (int i = 0; i < stacktop; i++) {
Py_XDECREF(frame->localsplus[i]);
}
Py_CLEAR(frame->f_locals);
}

void
_PyFrame_ClearExceptCode(_PyInterpreterFrame *frame)
{
Expand All @@ -135,12 +147,8 @@ _PyFrame_ClearExceptCode(_PyInterpreterFrame *frame)
}
Py_DECREF(f);
}
assert(frame->stacktop >= 0);
for (int i = 0; i < frame->stacktop; i++) {
Py_XDECREF(frame->localsplus[i]);
}
_PyFrame_ClearLocals(frame);
Py_XDECREF(frame->frame_obj);
Py_XDECREF(frame->f_locals);
Py_DECREF(frame->f_funcobj);
}

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