Date: Wed, 26 Feb 1997 14:19:44 +0200 (IST)
From: Eli Zaretskii <eliz AT is DOT elta DOT co DOT il>
To: chojnacki <s709 AT ernie DOT icslab DOT agh DOT edu DOT pl>
cc: djgpp AT delorie DOT com
Subject: Re: strange thing with exit(0)
In-Reply-To: <199702252042.VAA04335@ernie.icslab.agh.edu.pl>
Message-ID: <Pine.SUN.3.91.970226141302.10395A-100000@is>
MIME-Version: 1.0
Content-Type: TEXT/PLAIN; charset=US-ASCII


On Tue, 25 Feb 1997, chojnacki wrote:

> I've encountered very strange something.
> After compiling enclosed below code with:
> gcc -o foo foo.c
> program hangs in function exit() ("Hello!" is printed).
> Function flushKeyboard is guilty but I don't know why.

The real strange thing is that your program at all works, because you
don't zero out the SS and SP members of the registers: 

> void  flushKeyboard()
> {
> _go32_dpmi_registers r;
>   r.h.ah=0x0c;
>   r.h.al=0;
    r.x.ss = r.x.sp = r.x.flags = 0;   <<<<<<<<<<<<<<<<<< missing line
>   _go32_dpmi_simulate_int(0x21,&r);
> }

The line marked ``missing'' should make the program work.  The DJGPP FAQ 
list explains this in section 18.3.

> The more strange thing is that program hangs only if
> the name of the coff file is three characters long.
> If I rename "foo" for e.g. "foo1" and run "go32 foo1"
> everything is O.K.
> I found also that if I remove line:
> SHELL=C:\COMMAND.COM C:\ /E:2000 /P
> from my config.sys file program works fine.

Since you don't zero SS:SP, they point to random memory location, and 
slight changes in the program and/or environment migh prevent it from 
crashing.