[SDL] Interesting SDL Parachute problem

[Eric Wittmann]

	Hi everyone.  I have a project I'm working on that's using SDL as
(among other things) a front-end to another application.  The SDL window
disappears when this other application is launched.  I've been using
Java along with an SDL JNI binding that I wrote a little while back.  To
make the SDL window go away temporarily, I simply quit SDL - then when I
need the window to open up again, I re-initialize SDL and reload all of
my graphics, etc.  

	The problem is that when SDL_Quit is called, it also calls
SDL_UninstallParachute, even though I initialize SDL with the
no-parachute flag.  This is fine, since the code seems to attempt to put
back any signal handlers that were already installed (unless the
previous handler was SDL_Parachute).

	However, from my experience with what I'm doing now, this doesn't
exactly..well...work.  :)  It appears that the JVM is installing its own
signal handlers, in particular a seg fault handler.  So the following
(very stupid) Java code will throw a NullPointerException:

	int [][] dumbass = new int[32][];
	int temp = dumbass[0][0];

	If I run the above code prior to calling SDL_Quit(), it throws the
exception.  However, if I run the code after calling SDL_Quit(), the JVM
explodes, throwing shrapnel in all directions.

	If I comment out SDL_UninstallParachute() in the SDL sources and
recompile, then everything works fine.  Note that if I make
SDL_UninstallParachute() set all of the signal handlers back to SIG_DFL,
then the JVM simply seg faults relatively quietly, rather than exploding
into little chunks.  I'm not 100% sure what the difference might be -
but was hoping someone would have a theory.

	Anyone have any thoughts on this?  I'm happy to write a simple sample
program or post code if it will help.  I have an easy workaround for the
problem, which is to call SDL_QuitSubsystem(SDL_INIT_EVERYTHING) instead
of SDL_Quit in my JNI code - but I'm just really curious about this and
can't figure it out.


Thanks!

Eric Wittmann
wittmann at snet.net