Bug 794874

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
libewf-20100226-4.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/2012-02-17/libewf-20100226-4.fc17/

I've manually reviewed the bugs.

Within the category "Reference count too low" the 3 issues reported appear to be true bugs: the code should probably be using
   Py_RETURN_NONE;
rather than:
  return ( Py_None );
in order to add one to the reference count of Py_None; otherwise repeated calls could crash the interpreter.

Within the category "Reference leaks":
  pyewf_file.c:pyewf_file_read:ob_refcnt of '*result_data' is 1 too high
     Looks like a true memory leak

  pyewf_file.c:pyewf_file_get_header_values:ob_refcnt of '*dictionary_object' is 1 too high
    Looks like a memory leak for the case when this code fails:
      libewf_get_header_value_identifier_size unable to retrieve header value identifier size

  pyewf.c:pyewf_open:ob_refcnt of '*file_arguments' is 1 too high
    Looks like a memory leak for the case when Py_BuildValue() fails

Within the category "Segfaults within error-handling paths": the first three issues look like genuine crashers that could occur under low memory conditions.  The fourth is one-time only on import, so is unlikely to happen.

Within the category "Returning (PyObject*)NULL without setting an exception" the issues reported may be just a false positive.

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):
libewf-20100226-4.fc17
gcc-python-plugin post-0.9 git 771455b3128b1323e80bdda53939d8d140a84c68 running the checker in an *f16* chroot