Re: refactoring basebackup.c (zstd workers)

On Sun, Mar 20, 2022 at 3:11 PM Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us> wrote:
> > Even after reading the man page for strtol, it's not clear to me that
> > this is needed. That page represents checking *endptr != '\0' as
> > sufficient to tell whether an error occurred.
>
> I'm not sure whose man page you looked at, but the POSIX standard [1]
> has a pretty clear opinion about this:
>
> Since 0, {LONG_MIN} or {LLONG_MIN}, and {LONG_MAX} or {LLONG_MAX} are
> returned on error and are also valid returns on success, an
> application wishing to check for error situations should set errno to
> 0, then call strtol() or strtoll(), then check errno.
>
> Checking *endptr != '\0' is for detecting whether there is trailing
> garbage after the number; which may be an error case or not as you
> choose, but it's a different matter.

I think I'm guilty of verbal inexactitude here but not bad coding.
Checking for *endptr != '\0', as I did, is not sufficient to detect
"whether an error occurred," as I alleged. But, in the part of my
response you didn't quote, I believe I made it clear that I only need
to detect garbage, not out-of-range values. And I think *endptr !=
'\0' will do that.

--
Robert Haas
EDB: http://www.enterprisedb.com