Re: c-strtod: handling of out-of-memory

[Eric Blake]

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According to Bruno Haible on 1/24/2009 3:44 AM:
> +   Return value:
> +   - If successful, return the value as a double or 'long double',
> +     respectively, and don't modify errno.
> +   - In case of overflow, return ±HUGE_VAL or ±HUGE_VALL, respectively, and
> +     set errno to ERANGE.
> +   - In case of underflow, return a value very near to 0 and set errno to
> +     ERANGE.
> +   - If the string does not start with a number at all, return 0 (and recall
> +     that if ENDPTR != NULL, *ENDPTR is set to NPTR).

POSIX allows (but not requires) strtod() to set errno to EINVAL in this
case.  Now for the question: is it useful to the client to guarantee that
EINVAL is set?  If it is useful behavior to guarantee that EINVAL is set
in this case, then we should enhance our .m4 tests to filter out system
strtod() that did not implement this option, and we should make our
documentation explicit that we guarantee something for our wrapper even
though POSIX doesn't for the original.  If not, then we should be careful
in how we word this, in case we defer to a system strtod() that does not
set EINVAL on an empty parse.

> +   - In case of other error, return 0 and set errno, for example to EINVAL
> +     or ENOMEM.  */

I think that POSIX is explicit that the only way to fail strtod() with
EINVAL is if nothing was parsed, but you already covered that in the line
above; therefore, this line should only mention ENOMEM.

- --
Don't work too hard, make some time for fun as well!

Eric Blake             address@hidden
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