Re: Segmentation fault in gtk2-perl-application

[muppet <scott asofyet org>]

On Mar 31, 2005, at 4:20 PM, Stephan Brunner wrote:

> Am Donnerstag 31 März 2005 04:33 schrieb muppet:
> > What versions of gtk+, glib, Gtk2, and Glib are you using?  what
> > OS/dist?
> I run Debian Sarge on x86; that came with gtk+ 2.6.2, glib 2.6.3, Gtk2 
> and
> Glib 1.062. My personal debug-build of Gtk2 and Glib is 1.080.
on Fedora 2 with glib-2.4.0, gtk+ 2.4.7, Glib/Gtk2 1.080, i can't seem 
to reproduce the failure with your script.
same results in my cvs sandbox, which has glib-2.6.5 and gtk+ 2.6.4.


> > Beyond that, seeing the code is really going to be necessary.
> Here it is -- to my own surprise, I was able to delete pretty much 
> everything
> of my script and still get the segfault. What's left is not more than 
> a very
> basic gtk2-app that does nothing else than prompt for a directory if 
> you
> select File->open directory or hit Ctrl-O:
what about this even shorter version?  does it still exhibit the same 
behavior?  (i merely replaced the UIManager gui with a simple window 
containing a button.  if this one still crashes, we can rule out 
UIManager interactions...)
-=-=-=-=-
#!/usr/bin/perl
use warnings;
use strict;
use Gtk2 '-init';

my $window = Gtk2::Window->new;
$window->signal_connect (destroy => sub { Gtk2->main_quit; });

my $button = Gtk2::Button->new ('click me');
$button->signal_connect (clicked => \&loadDir);
$window->add ($button);

$window->show_all;
Gtk2->main;

###
sub loadDir {
    print "Entering sub loadDir...\n";
    my $dlg = Gtk2::FileChooserDialog->new('Select directory', undef,
         'select-folder',
         'gtk-cancel' => 'cancel',
         'gtk-open' => 'ok');
    my $response = $dlg->run();
    if ($response ne 'ok') {
        print "You aborted.\n";
    }
    else {
        print 'You selected: >' . $dlg->get_filename . "<\n";
    }

    $dlg->destroy();
    print "Leaving sub loadDir...\n";
}
-=-=-=-=-


> The probability of getting the segfault depends on the directory 
> selected --
> there is a folder in my $HOME that almost always results in the 
> segfault.
what is the name of that folder?  does its name (or the names of its 
children) contain any non-ascii characters?  how many files are in that 
folder?


> For the above sample-script, I created a new backtrace which is much 
> shorter
> than the one I sent yesterday:
>
> (gdb) bt
> #0  0x40769d9c in gtk_path_bar_get_type () from 
> /usr/lib/libgtk-x11-2.0.so.0
the valgrind output confirms that there's memory corruption, 
specifically, using freed memory on the heap.  the fun part will be 
tracking down where and why that actually occurs...

> The above script is so short and simple that I am stunned it can 
> segfault.
heh.  try a script that merely creates a common dialog (one-liner) but 
doesn't first call Gtk2->init.  it blows up almost immediately because 
pango isn't initialized.  ;-)

--
I think it worked on the Wiley Coyote model of project management - if
at any point you looked down and realised what you were doing was
impossible then you'd instantly fail.
  -- Simon Wistow