dtrace discuss - Sep 2007 - How to trace dynamic loaded libraries?

Hi there,

I''ve been trying to figure out some PAM issue, however it''s
difficult to use dTrace on it, just because of the nature of PAM - it
dynamically loads libraries specified in /etc/pam.conf.

So if you specify the probes upon app startup, most pam* modules are not loaded
yet so they would not match any probes, Then it''ll be difficult to set
break points with mdb and use dtrace in the same time.

What''s the best practice of doing this kind of trace?

Thanks,

Sean


--
This message posted from opensolaris.org

Sean Liu wrote:
> Hi there,
> 
> I''ve been trying to figure out some PAM issue, however
it''s difficult to use dTrace on it, just because of the nature of PAM -
it dynamically loads libraries specified in /etc/pam.conf.
> 
> So if you specify the probes upon app startup, most pam* modules are not
loaded yet so they would not match any probes, Then it''ll be difficult
to set break points with mdb and use dtrace in the same time.
> 
> What''s the best practice of doing this kind of trace?
off the top of my head ...

I''d split this up in two:
1) a script that waits for modload to be called, if the library loaded is 
the one you need, system ("dtace ...") the second script:

2) trace your library.

HTH
Michael
-- 
Michael Schuster
Recursion, n.: see ''Recursion''

You may find the -Z option useful for this purpose. It will allow
you to enable probes that are not yet active. Remember to use the
full library name not just the alias.

HTH

Angelo


Sean Liu wrote:
> Hi there,
>
> I''ve been trying to figure out some PAM issue, however
it''s difficult to use dTrace on it, just because of the nature of PAM -
it dynamically loads libraries specified in /etc/pam.conf.
>
> So if you specify the probes upon app startup, most pam* modules are not
loaded yet so they would not match any probes, Then it''ll be difficult
to set break points with mdb and use dtrace in the same time.
>
> What''s the best practice of doing this kind of trace?
>
> Thanks,
>
> Sean
>
>
> --
> This message posted from opensolaris.org
> _______________________________________________
> dtrace-discuss mailing list
> dtrace-discuss at opensolaris.org
>