[Python-Dev] Coverity Scan

[Brett Cannon]

On Thu, Jul 25, 2013 at 6:56 PM, Christian Heimes <christian at python.org>wrote:

> Am 26.07.2013 00:32, schrieb Terry Reedy:
> > I found the answer here
> > https://docs.google.com/file/d/0B5wQCOK_TiRiMWVqQ0xPaDEzbkU/edit
> > Coverity Integrity Level 1 is 1 (defect/1000 lines)
> > Level 2 is .1 (we have passed that)
> > Level 3 is .01 + no major defects + <20% (all all defects?) false
> > positives as that is their normal rate.#
> >
> > A higher false positive rates requires auditing by Coverity. They claim
> > "A higher false positive rate indicates misconfiguration, usage of
> > unusual idioms, or incorrect diagnosis of a large number of defects."
> > They else add "or a flaw in our analysis."
> >
> > # Since false positives should stay constant as true positives are
> > reduced toward 0, false / all should tend toward 1 (100%) if I
> > understand the ratio correctly.
>
> About 40% of the dismissed cases are cause by a handful of issues. I
> have documented these issues as "known limitations"
> http://docs.python.org/devguide/coverity.html#known-limitations .
>
> For example about 35 false positives are related to PyLong_FromLong()
> and our small integer optimization. A correct modeling file would
> eliminate the false positive defects. My attempts don't work as hoped
> and I don't have access to all professional coverity tools to debug my
> trials.
>

Have you tried asking for help from Coverity? They have been rather nice so
far and they may be willing to just give us free help in getting the
modeling file set up properly.

-Brett


>
> Nearly 20 false positives are caused by Py_BuildValue("N"). I'm still
> astonished that Coverity understands Python's reference counting most of
> the time. :)
>
> Did I mention that we have almost reached Level 3? All major defects
> have been dealt with (one of them locally on the test machine until
> Larry pushes his patch soonish), 4 of 7 minor issues must be closed and
> our dismissed rate is just little over 20% (222 out of 1054 = 21%).
>
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://mail.python.org/pipermail/python-dev/attachments/20130726/3b6f07f0/attachment.html>