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From: "Juan Manuel Guerrero" <ST001906 AT HRZ1 DOT HRZ DOT TU-Darmstadt DOT De>
Organization: Darmstadt University of Technology
To: Eli Zaretskii <eliz AT is DOT elta DOT co DOT il>
Date: Wed, 20 Feb 2002 22:44:43 +0100
Subject: Re: SIGSEGV and strlwr/strupr
CC: djgpp-workers AT delorie DOT com
References: <271CA283011 AT HRZ1 DOT hrz DOT tu-darmstadt DOT de>
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Message-ID: <27CD28B3260@HRZ1.hrz.tu-darmstadt.de>
Reply-To: djgpp-workers AT delorie DOT com

On Wed, 20 Feb 2002, Eli Zaretskii wrote:
> On Wed, 20 Feb 2002, Juan Manuel Guerrero wrote:
> > It works OK as long as some kind of windows is used as dpmi server.
> > As soon as cwsdpmi is used, bison dies with an error=0004.
> > The reason is that strlwr() does not check if the passed pointer
> > is a NULL pointer. In this case the while-loop derefences a NULL pointer
> > producing the SIGSEGV. This is the reason why for certain combinations
> > of command-line options bison 1.32/33 breaks on plain dos.
> > The small patch below will fix this for strlwr and strupr (suffers from the
> > same bug).
>
> I think it is wrong to patch string-related library functions to protect 
> them from NULL pointers.  ALL string-related functions have the same 
> problem.  It is programmer's responsibility to avoid passing NULL 
> pointers to library functions, except in those cases where the function 
> is explicitly documented to be able to accept NULL pointers.
>
> So I think the real fix should be in Bison, not in the library.

OK. Fixed in bison and patch submitted to bison maintainers.

Regards,
Guerrero, Juan Manuel