Date: Sat, 24 Jan 2009 14:33:39 -0800 From: Doug Barton <dougb@FreeBSD.org> To: Oliver Fromme <olli@lurza.secnetix.de> Cc: freebsd-hackers@freebsd.org Subject: Re: freebsd-update's install_verify routine excessive stating Message-ID: <497B9743.6080109@FreeBSD.org> In-Reply-To: <200901232222.n0NMMAcS097663@lurza.secnetix.de> References: <200901232222.n0NMMAcS097663@lurza.secnetix.de>
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Oliver Fromme wrote:
> Doug Barton wrote:
> > Oliver Fromme wrote:
> > > I assume, with "this" you mean my solution to the slow
> > > shell loop problem (not quoted above), not Yoshihiro Ota's
> > > awk proposal?
> >
> > I meant the solution using comm, sorry. (I forgot to mention that I
> > would probably use cmp here, but that's a personal preference.)
>
> I see. No problem.
>
> However, I think cmp wouldn't work here, because cmp only
> detects whether there is a difference between two files.
>
> In this case we need to know if one file is a subset of
> the other: For every hash there must be a .gz file, but
> it doesn't hurt if there are more files. So the list of
> hashes can be a subset of the list of .gz files, they
> don't have to be equal.
Hrrmmm, that doesn't sound like a good thing to me. I would think that
the hash list is pretty useless if it doesn't cover all the files.
> While I were at it, I skimmed through the cmp source and
> found a bug (or inefficiency): When the -s option is
> specified (i.e. silent, exit code only), it would be
> sufficient to terminate when the first difference is
> encountered. But it always compares the whole files.
> I'll try to make a patch to improve this.
That would definitely be appreciated, I use cmp -s in several places
in portmaster where that speed-up would make a non-trivial difference.
If there is anything I can do to help please let me know.
Doug
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