Re: Fix overflow in DecodeInterval

Joseph Koshakow <koshy44(at)gmail(dot)com> writes:
> On Sun, Apr 3, 2022 at 12:03 PM Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us> wrote:
>> Oh ... a bit of testing says that strtod() on an empty string
>> succeeds (returning zero) on Linux, but fails with EINVAL on
>> AIX. The latter is a lot less surprising than the former,
>> so we'd better cope.

> I'm not sure I follow exactly. Where would we pass an empty
> string to strtod()? Wouldn't we be passing a string with a
> single character of '.'?

Oh, I was thinking that we passed "cp + 1" to strtod, but that
was just caffeine deprivation. You're right, what we are asking
it to parse is "." not "". The result is the same though:
per testing, AIX sets EINVAL and Linux doesn't.

> So I think we need to check that endptr has moved both after
> the call to strtoi64() and strtod().

I'm not sure we need to do that explicitly, given that there's
a check later as to whether endptr is pointing at \0; that will
fail if endptr wasn't advanced.

The fix I was loosely envisioning was to check for cp[1] == '\0'
and not bother calling strtod() in that case.

regards, tom lane