Samba debug

Andreas Schneider asn at
Mon Nov 28 09:47:27 UTC 2016

On Monday, 28 November 2016 15:08:50 CET Martin Schwenke wrote:
> Amitay and I are in the process of moving to (more directly) use
> Samba's debug support.  At the moment we are doing file and syslog
> logging using CTDB's own backends, which are hooked into debug.[ch]
> using the DEBUG_CALLBACK support.

Hey Martin,

thanks for looking into this mess!

> We have come across (at least!) a couple of idiosyncrasies in
> debug.[ch]...  :-)
> * Headers and messages can be interleaved in file logging
>   Header and message are written using 2 separate write() calls (via
>   dbghdrclass(), dbgtext()). So, if 2 processes are writing to the same
>   log file, then you can get <header1>, <header2>, <message1>,
>   <message2>... or other variations.
>   This could be improved if the above 2 functions added to the buffer
>   and a single write() was then used.
> * When logging to syslog, header information is duplicated
>   That is the date and time (and maybe PID, progname), are present in
>   the output of dbghdrclass() and syslog adds them as well.
>   All the backends other than file (syslog, systemd, lttng,
>   GPFS) probably add their own timestamps.
>   This could be improved by having dbghdrclass() omit these items and
>   have the file backend add those that are configured.
> For CTDB logging we only really want single-line messages, with an
> appropriate non-redundant header.  For file we want a header
> (date, time, progname, pid).  For syslog we want to send just a bare
> message and have syslog do the rest.
> Suggestions?  Ideas?  :-)

Please take a look into the options:

	debug prefix timestamp
	timestamp logs

They are related and are totally broken.

The suggestion I have is that we need tests for the debug system. We have 
features which do not work and nobody notices.

Testing debug is possible using the Mock object [1][2] support in cmocka [3].



Andreas Schneider                   GPG-ID: CC014E3D
Samba Team                             asn at

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