[Python-checkins] r60860 - python/trunk/Modules/_struct.c python/trunk/Modules/cStringIO.c

[Neal Norwitz]

Amaury,

Can you add test cases for both of these fixes?

Thanks,
n
--

On Sat, Feb 16, 2008 at 6:34 AM, amaury.forgeotdarc
<python-checkins at python.org> wrote:
> Author: amaury.forgeotdarc
>  Date: Sat Feb 16 15:34:57 2008
>  New Revision: 60860
>
>  Modified:
>    python/trunk/Modules/_struct.c
>    python/trunk/Modules/cStringIO.c
>  Log:
>  Crashers of the day: Py_CLEAR must be used when there is a chance that the
>  function can be called recursively.
>  This was discussed in issue1020188.
>
>  In python codebase, all occurrences of Py_[X]DECREF(xxx->yyy) are suspect,
>  except when they appear in tp_new or tp_dealloc functions, or when
>  the member cannot be of a user-defined class.
>  Note that tp_init is not safe.
>
>  I do have a (crashing) example for every changed line.
>  Is it worth adding them to the test suite?
>
>  Example:
>
>  class SpecialStr(str):
>     def __del__(self):
>         s.close()
>
>  import cStringIO
>  s = cStringIO.StringIO(SpecialStr("text"))
>  s.close() # Segfault
>
>
>
>  Modified: python/trunk/Modules/_struct.c
>  ==============================================================================
>  --- python/trunk/Modules/_struct.c      (original)
>  +++ python/trunk/Modules/_struct.c      Sat Feb 16 15:34:57 2008
>  @@ -1471,7 +1471,7 @@
>                 return -1;
>
>         Py_INCREF(o_format);
>  -       Py_XDECREF(soself->s_format);
>  +       Py_CLEAR(soself->s_format);
>         soself->s_format = o_format;
>
>         ret = prepare_s(soself);
>
>  Modified: python/trunk/Modules/cStringIO.c
>  ==============================================================================
>  --- python/trunk/Modules/cStringIO.c    (original)
>  +++ python/trunk/Modules/cStringIO.c    Sat Feb 16 15:34:57 2008
>  @@ -575,8 +575,7 @@
>
>   static PyObject *
>   I_close(Iobject *self, PyObject *unused) {
>  -        Py_XDECREF(self->pbuf);
>  -        self->pbuf = NULL;
>  +        Py_CLEAR(self->pbuf);
>          self->buf = NULL;
>
>          self->pos = self->string_size = 0;
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