remote XOpenDisplay in Solaris (SunOS 5.6)

[David Korn]

>-----Original Message-----
>From: Jerry Miller [ mailto:gmiller@cs.sunysb.edu ]
>Sent: 23 February 2001 16:16

>Does anyone have an idea why Motif applications that
>used to run either locally or with a remote display now
>only work locally, causing a Segmentation fault as soon
>as XtVaAppInitialize () (or its more primitive component,
>XOpenDisplay()) is called in a remote-display run?

  If something has suddenly changed like this, it's probably because 
you've installed a new library somewhere, which is being pulled in by
dynamic linking, and isn't compatible with the version the application
is expecting to find.

>the software do not have this problem.  When I
>#define out calls from main() to other local functions,
>I still have it bombing, unless I also comment out a
>number of calls to external functions from the local
>functions that are never called!

  The first thing that happens at startup of an application is that the
constructors for any C++ class objects of static storage duration are 
called automagically.  It sounds like the problem is in one of these
constructors, since removing the function calls from main doesn't make
any difference; these constructors are called before main starts, anyway.

  The reason that removing the calls in the other functions finally makes
it work is because when they've been removed, that gets rid of all the
references to a particular object module in the altered lib, which means
that it doesn't get pulled in at all by the linker, which means that its
static objects aren't pulled in, which means that the faulty constructor
isn't run.

  Note that if there is no C++ in the Motif/X libs you're using, this may
turn out not to be the explanation after all!

>meaningless, even in the unlikely event the
>debugger isn't introducing its own uncertainty
>(a la Heisenberg?)

  Look up 'heisenbug' in the jargon file :)

>Rather than waste any more time on trial and
>error, I thought I'd see whether there's a
>window manager guru out there who might
>have answers or suggestions.

  I'm not that, and nor do I really know a lot about the mysteries of 
dynamically linked libraries, but what I've suggested is certainly up 
there in the 'top five possibilities to investigate' list.  See if the
last modified date on any of your lib files is around the time when it all
stopped working.

    hth, 
     DaveK
-- 
we are not seats or eyeballs or end users or consumers.
we are human beings - and our reach exceeds your grasp.
                    deal with it.                      - cluetrain.org 


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