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Date: Mon, 19 Oct 2009 08:58:05 -0500
From: David Kelly <dkelly@hiwaay.net>
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Subject: Re: need C help, passing char buffer[] by-value....
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On Mon, Oct 19, 2009 at 05:43:44AM +0200, Polytropon wrote:
> On Sun, 18 Oct 2009 22:23:43 -0500, David Kelly <dkelly@hiwaay.net> wrote:
> > When not using a count to indicate how much data is in a char* you  
> > should always test for null. Testing for null is not a sure fire way  
> > to prevent buffer over runs but its better than nothing.
> 
> There are means like
> 
> 	#include <assert.h>
> 	...
> 	assert(s);
> 
> to make sure s is not NULL, or testing for it explicitely like
> 
> 	if(!s)
> 		... error handling here ...

You are missing my point that *s == 0 is not a good out of bounds range
check.

> is possible. Furthermore, it is a proven way to give a length
> argument along with the (char *) argument, such as the "new"
> l-functions for strings, e. g. strlcat() and strlcpy(), do.
> 
> 	char *skiptags(char *s, int l);
> 
> You can even double-check for l begin != 0. Or you employ a
> test with strlen() function-internally.

strlen() knows nothing about the buffer allocation. As I originally
said, testing for null (and my example tested) is not foolproof but its
better than nothing. One should *also* test for the known end of the
allocated buffer.

-- 
David Kelly N4HHE, dkelly@HiWAAY.net
========================================================================
Whom computers would destroy, they must first drive mad.