Re: Strange interval arithmetic

Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us> writes:

> Michael Fuhr <mike(at)fuhr(dot)org> writes:
> > I usually check both in my own code but I noticed several places
> > where PostgreSQL doesn't, so I kept that style. I'll check both
> > if that's preferred.
>
> I'd say not --- it's more code and it makes a possibly unwarranted
> assumption about strtol's behavior.
>

Generally speaking looking at errno when you haven't received an error return
from a libc function is asking for trouble. It could be leftover from any
previous libc error.

That's how you get programs saying things like "strtol: No such file or
directory" ...

The strtol() function returns the result of the conversion, unless the value
would underflow or overflow. If an underflow occurs, strtol() returns
LONG_MIN. If an overflow occurs, strtol() returns LONG_MAX. In both cases,
errno is set to ERANGE. Precisely the same holds for strtoll() (with LLONG_MIN
and LLONG_MAX instead of LONG_MIN and LONG_MAX).

--
greg