Am 26.07.2013 14:56, schrieb Eli Bendersky:
> Just a quick question - is there a chance to convince Coverity to detect
> Python refcounting leaks in C API code :-) ? This could be useful not
> only for Python but for extensions too. As it stands now, Coverity's
> leak detection is Python must be pretty weak because almost everything
> is done via PyObject refcounts.

Coverity is able to detect some cases of refcount leaks. I don't know if
the software is able to keep track of all reference counts. But it
understands missing Py_DECREF() in error branches.

For example:

PyObject *n = PyLong_FromLong(0);
PyObject *u = PyUnicode_FromString("example");

if (u == NULL) {
� � return NULL;
� � /* Coverity detects that 'n' leaks memory */
}

Interesting. 

I was thinking of something more general though. Especially if we can mark function arguments and return values as stealing references / creating new ones / etc, many many common refcount bugs can be detected with static analysis. This is definitely research-y, probably too much for our current stage of relationship with Coverity :)
">

(original) (raw)




On Fri, Jul 26, 2013 at 7:29 AM, Christian Heimes <christian@python.org> wrote:
Am 26.07.2013 14:56, schrieb Eli Bendersky:
> Just a quick question - is there a chance to convince Coverity to detect
\> Python refcounting leaks in C API code :-) ? This could be useful not
\> only for Python but for extensions too. As it stands now, Coverity's
\> leak detection is Python must be pretty weak because almost everything
\> is done via PyObject refcounts.

Coverity is able to detect some cases of refcount leaks. I don't know if
the software is able to keep track of all reference counts. But it
understands missing Py\_DECREF() in error branches.

For example:

PyObject \*n = PyLong\_FromLong(0);
PyObject \*u = PyUnicode\_FromString("example");

if (u == NULL) {
� � return NULL;
� � /\* Coverity detects that 'n' leaks memory \*/
}

Interesting.

I was thinking of something more general though. Especially if we can mark function arguments and return values as stealing references / creating new ones / etc, many many common refcount bugs can be detected with static analysis. This is definitely research-y, probably too much for our current stage of relationship with Coverity :)


Eli




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