Strategies to debug cpython modules during provision

[Andrew Bartlett]

On Tue, 2018-04-10 at 11:36 +1000, William Brown wrote:
> > > 
> > > Inspecting the code, I see this is from password_hash.c's call to
> > > smb_krb5_init_context, and reading that code in
> > > source4/auth/kerberos/krb5_init_context.c between
> > > smb_krb5_init_context
> > > and smb_krb5_init_context_basic I can see some areas that *could*
> > > be
> > > the cause of the issue with regard to the system krb5.conf from MIT
> > > vs
> > > embedded heimdal.
> > 
> > Yep, the includedir statement.  A better error message would be good,
> > as would be backporting the patch for includedir from modern Heimdal.
> 
> Well, first the issue is we see "ldb operations error". A good error
> message should communicate more to the admin so that they have an
> understanding of what to do next. Something like "unable to parse
> krb5.conf" would be much better than just "operations error". 

Indeed. 

> Sadly, looking at it, when we get ret = 22, which I assume here is
> KRB5_CONFIG_BADFORMAT, we just wrap that into the ldb_operr(ldb) macro,
> so we lose all the context that could help communicate the error to
> someone.

Correct.

> So the first issue is how can we communicate what went wrong, why it
> went wrong, and how to resolve it. 

Exactly.

> After that, then we can think about "modern heimdal" to prevent the
> error at all. 

Agreed.

> Given how unfamiliar I am with the codebase though, I'd like some
> advice on where to start here and how to communicate better. I'm
> assuming this requires a call to ldb_error instead of ldb_operr()
> macro. Does that sound like a reasonable start to resolve this? 

ldb_asprintf_errstring() would be the best way to fill out a good error
string. 


> Done. Worked out the root cause now. Thank you! 

I do appreciate your attention on these things - we often inflict pain
on new users, and they would like these things fixed, but rarely do our
new users come with the coding skill to fix them.

Thank you very much,

Andrew Bartlett

-- 
Andrew Bartlett
https://samba.org/~abartlet/
Authentication Developer, Samba Team         https://samba.org
Samba Development and Support, Catalyst IT   
https://catalyst.net.nz/services/samba