Re: [LTP] [PATCH v2 1/2] lib/safe_macros: Add SAFE_STRTOF

[zhaogongyi via ltp <ltp@lists.linux.it>]

Hi Cyril,

> 
> Hi!
> > +float safe_strtof(const char *file, const int lineno,
> > +		  void (cleanup_fn) (void), char *str,
> > +		  float min, float max)
> > +{
> > +	float rval;
> > +	char *endptr;
> > +
> > +	errno = 0;
> > +	rval = strtof(str, &endptr);
> > +
> > +	if ((errno == ERANGE) || (rval == 0)
> > +	    || (rval == HUGE_VAL) || (rval == -HUGE_VAL)) {
> 
> This does not look right, supposedly the ERANGE is only set on overflow,
> and the rval is not guaranteed to be exact on underflow. Also rval == 0 is a
> valid result.
>

According to man 3 strtof, it seems there are some cases like:

1. strtof return the converted value as normal
2. strtof return 0 when no conversion is performed, and endptr == nptr:  'rval == 0'
3. strtof return HUGE_VAL or -HUGE_VAL when overflow:      '(rval == HUGE_VAL) || (rval == -HUGE_VAL)'
4. strtof retrun 0 and set errno to ERANGE when underflow:   'errno == ERANGE'


For 2, it seems need to add checking of endptr when 'rval == 0' like:  (rval == 0 && !strcmp(endptr, nptr)
	
Other places seem to be fine.


Regards,
Gongyi

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