Segfault bug in SoBlinker

[Ben Wong <benjamin.wong@xxxxxxxxxxxxx>]

Hi,

It appears that if you allocate an SoBlinker before calling
SoXt::init(), the program will die with a segmentation fault. This
doesn't appear to be documented anywhere, nor mentioned on any
web-page, so I assume it is a bug rather than an obscure feature.
(Of course, it could just be me doing something silly, but it seems
unlikely at this point).

I have reproduced the bug on both NetBSD-1.5 with the LGPL version of
Open Inventor-2.1.5-7 and on an SGI running IRIX 6.5 (with the stock
Open Inventor). Both died with the same call stack (see below). I'd
like to know if this bug still exists in the latest version of Open
Inventor. Could someone please test it for me and post the results?

Below I have included a minimal program to reproduce the bug. Comment
out the line that defines BLINKBUG if you want to see the program run
without dumping core.

        Ben

--
                                        College of Computing and GVU
Benjamin.Wong@xxxxxxxxxxxxx             Georgia Institute of Technology
                                        Atlanta, Georgia 30332-0280

-------- 8< -------- CUT HERE -------- 8< -------- CUT HERE -------- 

#include <stdlib.h>
#include <Inventor/SoDB.h>
#include <Inventor/SoInput.h>
#include <Inventor/Xt/SoXt.h>
#include <Inventor/Xt/SoXtRenderArea.h>
#include <Inventor/nodes/SoBlinker.h>
#include <Inventor/nodes/SoDirectionalLight.h>
#include <Inventor/nodes/SoMaterial.h>
#include <Inventor/nodes/SoPerspectiveCamera.h>
#include <Inventor/nodes/SoSeparator.h>
#include <Inventor/nodes/SoCube.h>


#define BLINKBUG

// This program exercises a bug in Open Inventor such that if an
// SoBlinker is allocated *before* SoXt::init() is called, the program
// will have a segmentation fault.
  
// This bug was demonstrated on both g++ with Open Inventor 2.1.5-7
// (NetBSD), and CC with IRIX 6.5's standard Open Inventor.
//
// Both die with the same call stack:

//(gdb) bt
//#0  SbDict::findEntry () at SbDict.c++:182
//#1  0xc87d3e8 in SbDict::find () at SbDict.c++:160
//#2  0xc926f34 in find__13SoGlobalFieldSGRC6SbName () at SoGlobalField.c++:198
//#3  0xc88af34 in getGlobalField__4SoDBSGRC6SbName () at SoDB.c++:827
//#4  0xc8de5e4 in SoTimeCounter::__ct () at SoTimeCounter.c++:55
//#5  0xc9354d8 in SoBlinker::__ct () at SoBlinker.c++:43
//#6  0x10001c40 in main (argv=0x7fff2f24) at minblinker.cc:25


void
main(int , char **argv)
{
#ifdef BLINKBUG
SoBlinker *myBlinker = new SoBlinker;   // THIS CORE DUMPS!
#endif


   // Initialize Inventor and Xt
   Widget myWindow = SoXt::init(argv[0]);  
   if (myWindow == NULL) exit(1);     


#ifndef BLINKBUG
SoBlinker *myBlinker = new SoBlinker;   // BUT LATER ALLOCATION IS FINE.
#endif


   // Set up camera and light
   SoSeparator *root = new SoSeparator;
   root->ref();
   SoPerspectiveCamera *myCamera = new SoPerspectiveCamera;
   root->addChild(myCamera);
   root->addChild(new SoDirectionalLight);

   // Setup the scene graph
   root->addChild(myBlinker);
   myBlinker->speed = 1.0/2;  // blink every two seconds
   myBlinker->addChild(new SoCube);

   // Set up and display render area 
   SoXtRenderArea *myRenderArea = new SoXtRenderArea(myWindow);
   SbViewportRegion myRegion(myRenderArea->getSize()); 
   myCamera->viewAll(root, myRegion);

   myRenderArea->setSceneGraph(root);
   myRenderArea->setTitle("Minimal SoBlinker Implementation");
   myRenderArea->show();
   SoXt::show(myWindow);
   SoXt::mainLoop();
}