[syslinux] [PATCH] chrreplace: Don't skip the first character

[Josh Triplett]

On Mon, Jun 15, 2015 at 08:57:24PM +0300, Ady wrote:
> 
> > Check if the first character matches the character to replace, rather
> > than skipping it and starting with the second.
> > 
> > Signed-off-by: Josh Triplett <josh at joshtriplett.org>
> > ---
> > 
> > I'm assuming, based on a look at the callers, that this is not
> > intentional, and that it just happened that none of the callers happened
> > to ever need to replace the first character.
> > 
> >  com32/lib/chrreplace.c | 2 +-
> >  1 file changed, 1 insertion(+), 1 deletion(-)
> > 
> > diff --git a/com32/lib/chrreplace.c b/com32/lib/chrreplace.c
> > index 65786f9..cfbf5d4 100644
> > --- a/com32/lib/chrreplace.c
> > +++ b/com32/lib/chrreplace.c
> > @@ -4,8 +4,8 @@
> >  void chrreplace(char *source, char old, char new) 
> >  {
> >      while (*source) { 
> > -	source++;
> >  	if (source[0] == old) source[0]=new;
> > +	source++;
> >      }
> >  }
> >  
> > -- 
> > 2.1.4
> > 
>  
> May I ask, where is this code having some effect?
> 
> Is there some way to trigger certain issue / effect / behavior with the 
> code as in version 6.03 that would be corrected / improved by this 
> patch?
> 
> Which would be the context / setup / config where some issue related to 
> this code could be triggered?
> 
> I am not criticizing the patch. I just would like to know, in the eyes 
> of a final user, what / where the effect of the code as found in v.6.03 
> could be seen, and the effect of this patch.

To the best of my knowledge, this doesn't cause any user-visible bug in
syslinux; as mentioned above, all the callers happen to never need to
replace the first character.  However, it's also very surprising and
undocumented behavior; I only found it while digging through the
available com32 libraries to find out which memory and string functions
were available.  If this behavior is intentional, it needs a pile of
documentation and a good explanation for why skipping the first
character is useful.

- Josh Triplett