Re: [PATCH] Put sha1dc on a diet

[Linus Torvalds <torvalds@linux-foundation.org>]

On Wed, Mar 1, 2017 at 10:42 AM, Junio C Hamano <gitster@pobox.com> wrote:
> I see //c99 comments

sha1dc is already full of // style comments. I just followed the
existing practice.

> and also T array[] = { [58] = val } both of
> which I think we stay away from (and the former is from the initial
> import), so some people on other platforms MAY have trouble with
> this topic.

Hmm. The "{ [58] = val; }" kind of initialization would be easy to
work around by just filling in everything else with NULL, but it would
make for a pretty nasty readability issue.

That said, if you mis-count the NULL's, the end result will pretty
immediately SIGSEGV, so I guess it wouldn't be much of a maintenance
problem.

But if you're just willing to take the "let's see" approach, I think
the explicitly numbered initializer is much better.

The main people who I assume would really want to use the sha1dc
library are hosting places. And they won't be using crazy compilers
from the last century.

That said, I think that it would be lovely to just default to
USE_SHA1DC and just put the whole attack behind us. Yes, it's slower.
No, it doesn't really seem to matter that much in practice.

              Linus