Re: [Jack-Devel] jack2 turned verbose

Brendan Jones <brendan.jones.it@xxxxxxxxx> · Sun, 03 Jun 2012 22:52:10 +0200

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



I've come a cross a jackdbus error which seems related. Basically 

jackbus receives a SIGSEGV via the dbus-daemon on account of a bool 

value not being 1 or 0.



The crude workaround below does nothing to explain the issue. Using a 

struct in this instance is also not possible:


diff -Nurp jack-1.9.8.orig/dbus/jackdbus.c jack-1.9.8/dbus/jackdbus.c

--- jack-1.9.8.orig/dbus/jackdbus.c	2011-12-19 12:54:24.000000000 +0100
+++ jack-1.9.8/dbus/jackdbus.c	2012-06-03 22:06:16.148799580 +0200
@@ -418,6 +418,7 @@ jack_dbus_message_append_variant(
     }

     /* Append the supplied value. */
+    if (type == DBUS_TYPE_BOOLEAN) *arg = (message_arg_t) ((int*)arg>0);

     if (!dbus_message_iter_append_basic (&sub_iter, type, (const void 

*) arg))

     {
         dbus_message_iter_close_container (iter, &sub_iter);

Where arg is a pointer to (dbus/jackdbus.h)
typedef union
{
    unsigned char byte;
    dbus_bool_t boolean;
    dbus_int16_t int16;
    dbus_uint16_t uint16;
    dbus_int32_t int32;
    dbus_uint32_t uint32;
    dbus_int64_t int64;
    dbus_uint64_t uint64;
    double doubl;
    const char *string;
} message_arg_t;



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