Re: [RFC] Fix eir parsing function.

[Szymon Janc <szymon.janc@tieto.com>]

Hi,

> Hi Andrei,
> 
> On Fri, Nov 29, 2013, Andrei Emeltchenko wrote:
> > Currently eir_parse always return 0 but it is checked throughout the
> > code (in android/bluetooth code as well in src/adapteri, etc) for
> > return value (err < 0) which never happens. Return -1 if there is
> > nothing to parse. Send as RFC as I do not know how current code supposed
> > to be working.
> > ---
> >  src/eir.c | 2 +-
> >  1 file changed, 1 insertion(+), 1 deletion(-)
> > 
> > diff --git a/src/eir.c b/src/eir.c
> > index 084884e..f7450c9 100644
> > --- a/src/eir.c
> > +++ b/src/eir.c
> > @@ -138,7 +138,7 @@ int eir_parse(struct eir_data *eir, const uint8_t *eir_data, uint8_t eir_len)
> >  
> >  	/* No EIR data to parse */
> >  	if (eir_data == NULL)
> > -		return 0;
> > +		return -1;
> >  
> >  	while (len < eir_len - 1) {
> >  		uint8_t field_len = eir_data[0];
> 
> I think the only concern here is "when is it safe to call
> eir_data_free()?". If it would not be safe to call that in case the
> eir_parse function "fails" then we'd need to be able to clearly
> distinguish failure though a -1 return value. However, as it now stands
> it is always safe to call eir_data_free() on a struct that was passed to
> eir_parse(), so I'd go for simply changing this function to return void
> instead of int.

I think it should be possible to check if parsing failed due to invalid EIR
but I think parsing empty EIR should not result in error.

Most callers do verify eir_len or buffer validity before calling eir_parse()
anyway so I would change this  check to:
if (!eir_data || !eir_len) return 0; 

and simplify callers code.

-- 
BR
Szymon Janc