Re: [PATCH v4 2/5] t5000: test tar files that overflow ustar headers

From: Jeff King <peff@peff.net>
Date: Jul 14, 2016, 20:27 UTC
Message-ID: <20160714202727.GA19101@sigill.intra.peff.net>
In-Reply-To: <xmqqbn20otqu.fsf@gitster.mtv.corp.google.com>

On Thu, Jul 14, 2016 at 01:22:01PM -0700, Junio C Hamano wrote:

Show 8 quoted lines

> > Also, shouldn't it be checking against 0xFFFFFFFF?
> 
> Correct.  Somehow I thought I was checking with LONG_MAX.  Will correct.
> 
> > An easier check would be "sizeof()", but I guess we can't use that in a
> > preprocessor directive.
> 
> Yes, I tried it and failed ;-)

I also found it funny that you used "==" instead "<=", but I cannot really think of a case where it would matter. If it is "<= 0xFFFFFFFF", that basically covers 16-bit platforms. I really hope nobody is trying to run git on such a platform. Doing "< 0xFFFFFFFFFFFFFFFF" to check for "less than 64-bit" would make more sense, but would probably choke on a 32-bit preprocessor.

So that everybody is either 32- or 64-bit these days, I think it doesn't matter in practice.

Show 18 quoted lines

> >> -test_expect_success TAR_HUGE 'system tar can read our huge size' '
> >> +test_expect_success TAR_HUGE,64BIT 'system tar can read our huge size' '
> >
> > The 64BIT prereq is really "unsigned long is 64-bit". I wonder if we
> > should call it UL64 or something like that to make it more clear.
> >
> > That makes it unnecessarily tied-in with the implementation, but it does
> > make it more clear what we care about; the distinction matters for
> > things like LP64 vs LLP64.
> 
> I do not think any platform is weird enough to have different sizes
> for long and ulong, so I am not sure you need UL64.
> 
> But pointer size can legitimately be different, so it has a value to
> differentiate between LP64 and LLP64, if we start doing things like
> "does this platform have large virtual address space?"
> 
> LONG_IS_64BIT perhaps to be more readable?

Yeah, that is what I was trying to get at, but you stated it much more clearly. LONG_IS_64BIT is good. I wonder if the "git version --build-options" should be "sizeof-long", too. It's shorter, and indicates our assumption that we are talking about all longs, not just unsigned ones.

-Peff