[LAU] [Jack-Devel] jack2 turned verbose

Robin Gareus robin at gareus.org
Fri Jun 1 13:58:53 UTC 2012

Hi David,

On 06/01/2012 03:48 PM, David Adler wrote:
> On Fri, Jun 1, 2012 at 2:52 PM, Robin Gareus wrote:
>> It might have to do with Arch's compiler[-flags] and how jack2 uses
>> unions .. or scoping: JackGlobals vs Engine-Parameters.. although I
>> don't have an explanation.. all seems good.
> Compiler flags (for 32bit) are, (from unaltered /etc/makepkg.conf):
> CXXFLAGS="-march=i686 -mtune=generic -O2 -pipe -fstack-protector
> --param=ssp-buffer-size=4 -D_FORTIFY_SOURCE=2"
>> A hunch: it could be caused by using 'server_ptr->verbose.b' (a union)
>> as boolean. The sever only checks "if (server_ptr->verbose.b)". The
>> union itself comprises other uninitialized values that could make it
>> evaluate to true (though it shouldn't, but maybe some compiler
>> optimization casts it to (int) instead of (bool) )
>> I know this is the '-users' list (I'm ccing jack-devel), but could
>> someone who experiences the problem try to track it down?
>> Basically just add a few printf()'s. Start at: common/JackControlAPI.cpp
>> - line 926 - before the call to  "new JackServer(..)" add
>>  printf("DEBUG verbose: %s\n",(server_ptr->verbose.b)?"on":"off");
>> recompile, launch jackd. If it prints "verbose: on", sth is wrong with
>> parameter initialization in main() or with using unions. If it's "off"
>> the problem sits deeper:
> DEBUG verbose: on
>> add a line just after common/JackServer.cpp line 66
>>  printf("DEBUG verbose2: %s\n",(JackGlobals::fVerbose)?"on":"off");
>> ...
> above, your line number didn't match exactly, so we seem to have
> different versions (1.9.7 here). Thus, I wasn't exactly sure where to
> add the prinf() and did the following:
> ...
>     JackServerGlobals::fUserCount = 1;     // One user
>     printf("DEBUG verbose2: %s\n",(JackGlobals::fVerbose)?"on":"off");
>     JackGlobals::fVerbose = verbose;
>     printf("DEBUG verbose3: %s\n",(JackGlobals::fVerbose)?"on":"off");
> }
> which prints:
> DEBUG verbose2: off
> DEBUG verbose3: on
>> A crude test for the union() hunch would be to change
>> common/JackControlAPI.h line 53:
>>  replace
>>  "union jackctl_parameter_value"
>> with
>>  "struct jackctl_parameter_value"
>> and compile with '-fpermissive' like this:
>>  CXXFLAGS="-fpermissive" ./waf  configure
>>  ./waf
> Again, mismatching line numbers. I assume you meant the line:
> union jackctl_parameter_value verbose;
> Changing that to struct fixes both issues I reported,
> the verbose output and exit on last client close.
> So we seem to be getting somewhere. Nice.
> thanks Robin,
> d

just a quick re: the line-numbers refered to git-head
currently 007cdc37142a

It looks like it is indeed caused by using unions to check for /true/.
  "if ([bool/int/..]union) -> always true"

But I'm at a loss what'd cause those issues and how to best fix it.
Maybe someone else can take it from here. It should be sufficient info
to file a bug report at  https://github.com/jackaudio/jack2/issues


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