Bug 800154

Description of problem:
I've been writing an experimental static analysis tool to detect bugs commonly occurring within C Python extension modules:
  https://fedorahosted.org/gcc-python-plugin/
  http://gcc-python-plugin.readthedocs.org/en/latest/cpychecker.html
  http://fedoraproject.org/wiki/Features/StaticAnalysisOfPythonRefcounts

I ran the latest version of the tool (in git master; post 0.9) on
python-iwlib-1.1-2.fc17.src.rpm, and it reports various errors.

You can see a list of errors here, triaged into categories (from most significant to least significant):
http://fedorapeople.org/~dmalcolm/gcc-python-plugin/2012-03-05/python-iwlib-1.1-2.fc17/

I've manually reviewed the issues reported by the tool; all of them appear to relate to code of this form:

   PyDict_SetItem(dict,
                  PyString_FromString("some_key"),
                  PyString_FromString(buffer));

This will leak references: PyDict_SetItem() adds new references to the key and the value, it doesn't steal references to the inputs.

Also, PyString_FromString() can fail under low memory conditions, returning NULL, and PyDict_SetItem(dict, NULL, ...) or PyDict_SetItem(dict, ..., NULL) will segfault.

(the use of PyDict_SetItemString() would simplify this code, removing two sets of errors).

There may of course be other bugs in my checker tool.

Hope this is helpful; let me know if you need help reading the logs that the tool generates - I know that it could use some improvement.

Version-Release number of selected component (if applicable):
python-iwlib-1.1-2.fc17
gcc-python-plugin post-0.9 git 11462291a66c8db693c8884cb84b795bb5988ffb running the checker in an *f16* chroot