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| author | Fred Drake <fdrake@acm.org> | 2004-02-04 23:14:14 +0000 |
|---|---|---|
| committer | Fred Drake <fdrake@acm.org> | 2004-02-04 23:14:14 +0000 |
| commit | e5e6a15cb88d65de7b6bdca8dba6cffbbab2b469 (patch) | |
| tree | 4c17c6ad0d14c33d8138d3b23869969b757691bb /Objects/weakrefobject.c | |
| parent | 0f8e2af957f01a05ffe8d768c7bb1441c1bb8b41 (diff) | |
| download | cpython-e5e6a15cb88d65de7b6bdca8dba6cffbbab2b469.tar.gz | |
Allocating a new weakref object can cause existing weakref objects for
the same object to be collected by the cyclic GC support if they are
only referenced by a cycle. If the weakref being collected was one of
the weakrefs without callbacks, some local variables for the
constructor became invalid and have to be re-computed.
The test caused a segfault under a debug build without the fix applied.
Diffstat (limited to 'Objects/weakrefobject.c')
| -rw-r--r-- | Objects/weakrefobject.c | 19 |
1 files changed, 16 insertions, 3 deletions
diff --git a/Objects/weakrefobject.c b/Objects/weakrefobject.c index cf0316a50f..575a928f75 100644 --- a/Objects/weakrefobject.c +++ b/Objects/weakrefobject.c @@ -630,16 +630,23 @@ PyWeakref_NewRef(PyObject *ob, PyObject *callback) /* return existing weak reference if it exists */ result = ref; if (result != NULL) - Py_XINCREF(result); + Py_INCREF(result); else { + /* Note: new_weakref() can trigger cyclic GC, so the weakref + list on ob can be mutated. This means that the ref and + proxy pointers we got back earlier may have been collected, + so we need to compute these values again before we use + them. */ result = new_weakref(ob, callback); if (result != NULL) { if (callback == NULL) { insert_head(result, list); } else { - PyWeakReference *prev = (proxy == NULL) ? ref : proxy; + PyWeakReference *prev; + get_basic_refs(*list, &ref, &proxy); + prev = (proxy == NULL) ? ref : proxy; if (prev == NULL) insert_head(result, list); else @@ -672,8 +679,13 @@ PyWeakref_NewProxy(PyObject *ob, PyObject *callback) /* attempt to return an existing weak reference if it exists */ result = proxy; if (result != NULL) - Py_XINCREF(result); + Py_INCREF(result); else { + /* Note: new_weakref() can trigger cyclic GC, so the weakref + list on ob can be mutated. This means that the ref and + proxy pointers we got back earlier may have been collected, + so we need to compute these values again before we use + them. */ result = new_weakref(ob, callback); if (result != NULL) { PyWeakReference *prev; @@ -682,6 +694,7 @@ PyWeakref_NewProxy(PyObject *ob, PyObject *callback) result->ob_type = &_PyWeakref_CallableProxyType; else result->ob_type = &_PyWeakref_ProxyType; + get_basic_refs(*list, &ref, &proxy); if (callback == NULL) prev = ref; else |