Re: Lost Pointer when adding GTK+ to an application

["Diego Rivera" <rive17 gmail com>]

Thanks for the quick answer, however, the GTK+ component is the same process
as the Console application. The console application checks for some
arguments and finishes by calling the working function of the application
with parameters that reflect the arguments received from the console. My
GtkButton callback just calls this last function with some parameters i have
selected.

So no inter-process communication is requiered

Thanks for the suggestion anyway

-Diego--

On Wed, May 7, 2008 at 8:55 PM, James Scott Jr <skoona verizon net> wrote:

> On Wed, 2008-05-07 at 20:33 -0600, Diego Rivera wrote:
> > Hi! I am not exactly new to GTK+, however I have come across a problem i
> > have no explanation for, and I'll be glad if someone could point me
> towards
> > a possible solution.
> >
> > I am currently developing an application that uses various algorithms
> for
> > sequence alignment in biological applications (DNA, RNA, Proteins and so
> > on). This application is mainly for scientific purposes.
> >
> > The core algorithms are already running fine as a console application in
> a
> > very stable version. I am working in adding some graphical interface to
> the
> > program using GTK+. So, I built a little Window that asks for the
> different
> > parameters and makes a call to the already defined functions in the
> console
> > application, which are indeed stable. However, when making the call to
> the
> > algorithm with GTK+ running, some of the pointers in my data structures
> get
> > lost, and I just get a Segmentation Fault.
> >
> > While trying to debug this weird behavior, I have narrowed the problem
> to
> > the fact of having a window running.
> >
> > Right now, I just have a main that creates a GtkWindow with a GtkButton,
> and
> > the callback of the button calls the stable routine of the console
> > application using some "hard-wired" parameters. I have made tests and
> the
> > console application gives the correct answer for those parameters.
> However,
> > when calling the routine from the callback, Segmentation Fault is the
> only
> > result I have been able to get.
> >
> > I have tried with different versions of GTK+ and the outcome is
> persistent.
> > The data structure of the console application looks something like this:
> >
> > typedef struct{
> >     int length;
> >     char* seq;
> > }sequence_t;
> >
> > typedef struct{
> >     int n;
> >     int m;
> >     int** table;
> > }table_t;
> >
> > typedef struct{
> >     sequence_t* vp;
> >     sequence_t* wp;
> >     table_t* table;
> >     int scoring;
> >     int result;
> > }alignment_t;
> >
> > Using gdb i have found that the Segmentation Fault occurs at some point
> when
> > accesing the table from the alignment.
> >
> > I believe i have made no memory errors in my console application, since
> it
> > runs ok every time. However, i haven't seen the correct output from my
> GTK
> > application.
> >
> > Is there any hint that you could give me in order to correct the error?
> How did you add the GTK component to the existing console app; are they
> one process or two?
>
> Your segfault suggest that they are two separate processes.  In which
> case attempting to share memory elements will cause a segfault every
> time no matter how correct and hard-coded the structures.
>
> You may need to consider designing in and using some type of IPC
> (Inter-Process Communications) like a named-pipe, shared-memory, socket
> communications, memory queue, etc.  Something designed to communicate
> between two active processes.
>
> James,
>
> > Thanks
> > - Diego Rivera -
> > _______________________________________________
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