[Python-Dev] debugging test_importlib.test_bad_traverse - script status is SUCCESS - but FAIL is expected.

Michael aixtools at felt.demon.nl
Tue Sep 18 05:48:53 EDT 2018

On 17/09/2018 09:39, Michael wrote:
> I read the discussion related to issue32374. That seems to be sure that
> other events that could
> cause the test to fail (i.e., the program executes successfully) are
> caught early, and/or ignored
> so that the program fails - and the test succeeds.

After reading below, I would appreciate knowing whether to ask that
issue32374 be reopened and the test adjusted so that the test is
"SkipIf" AIX? Or, something else? I'll work on something else, but I do
not want to guess the current intent of this test module.


In: Modules/_testmultiphase.c - found where AIX and Linux differ
in their response to accessing a NULL pointer, in this case

  +624  static int
  +625  bad_traverse(PyObject *self, visitproc visit, void *arg) {
  +626      testmultiphase_state *m_state;
  +627     FILE *err = fopen("/tmp/err","a");
  +629      m_state = PyModule_GetState(self);
  +631  fprintf(err,"%s:%d\n", __FILE__,__LINE__); fflush(err);
  +632  fprintf(err, "m_state:08%lx &m_state->integer:%08lx\n",
  +633          m_state, &(m_state->integer));
  +634  fclose(err);
  +635      Py_VISIT(m_state->integer);
  +636  /*
  +637  #define Py_VISIT(op)
  +638      do {
  +639          if (m_state->integer) {
  +640              int vret = visit((PyObject *)(m_state->integer), arg);
  +641              if (vret) {
  +642                  return vret;
  +643              }
  +644          }
  +645      } while (0);
  +646  */
  +647      return 0;
  +648  }

The "m_state" and m_state->integer values are identical, but the
response is not.

root at x066:[/data/prj/python/git]uname
m_state:080 &m_state->integer:00000000

root at x074:/data/prj/python/git# uname
m_state:080 &m_state->integer:00000000

++++++ Test program to demonstrate +++++++
AIX does not segmentfault on access of a NULL pointer
root at x074:/data/prj/python/git# cat nullpr.c
        int *vpt = NULL;

fprintf(stdout, "vpt = %08lx\n", vpt);
if (*vpt)

root at x074:/data/prj/python/git# rm -f nullpr; make nullpr; ./nullpr
make: Warning: File 'nullpr.c' has modification time 387 s in the future
cc     nullpr.c   -o nullpr
nullpr.c:2:1: warning: return type defaults to 'int' [-Wimplicit-int]
make: warning:  Clock skew detected.  Your build may be incomplete.
vpt = 00000000
Segmentation fault

++++++++++ AIX does not 'Segmenttation fault' +++++++++++++
root at x066:[/data/prj/python/git]rm -r nullpr; make nullpr; ./nullpr
cc     nullpr.c   -o nullpr
vpt = 00000000

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