From: "Ævar Arnfjörð Bjarmason" <avarab@gmail.com>
To: Johannes Schindelin <Johannes.Schindelin@gmx.de>
Cc: Junio C Hamano <gitster@pobox.com>,
Carlo Arenas <carenas@gmail.com>,
git@vger.kernel.org
Subject: Re: [PATCH] grep: skip UTF8 checks explicitally
Date: Fri, 26 Jul 2019 17:15:25 +0200 [thread overview]
Message-ID: <87ef2c7roy.fsf@evledraar.gmail.com> (raw)
In-Reply-To: <nycvar.QRO.7.76.6.1907252021230.21907@tvgsbejvaqbjf.bet>
On Thu, Jul 25 2019, Johannes Schindelin wrote:
> Hi Junio,
>
> On Thu, 25 Jul 2019, Junio C Hamano wrote:
>
>> Johannes Schindelin <Johannes.Schindelin@gmx.de> writes:
>>
>> >> OK, in short, barfing and stopping is a problem, but that flag is
>> >> not the right knob to tweak. And the right knob ...
>> >>
>> >> > 1) We're oversupplying PCRE2_UTF now, and one such case is what's being
>> >> > reported here. I.e. there's no reason I can think of for why a
>> >> > fixed-string pattern should need PCRE2_UTF set when not combined
>> >> > with --ignore-case. We can just not do that, but maybe I'm missing
>> >> > something there.
>> >> >
>> >> > 2) We can do "try utf8, and fallback". A more advanced version of this
>> >> > is what the new PCRE2_MATCH_INVALID_UTF flag (mentioned upthread)
>> >> > does. I was thinking something closer to just carrying two compiled
>> >> > patterns, and falling back on the ~PCRE2_UTF one if we get a
>> >> > PCRE2_ERROR_UTF8_* error.
>> >>
>> >> ... lies somewhere along that line. I think that is very sensible.
>> >
>> > I am glad that everybody agrees with my original comment on ab/no-kwset
>> > where I suggested that we should use our knowledge of the encoding of
>> > the haystack and convert it to UTF-8 if we detect that the pattern is
>> > UTF-8 encoded,...
>>
>> Please do not count me among "everybody", then. I did not think
>> that Ævar meant to iconv the haystack when I wrote the message you
>> are responding to, but if that was what he meant, I would not have
>> said "very sensible".
>
> Okay, but in that case I cannot agree with your assessment that it is
> very sensible.
FWIW what I meant was not that we'd run around and iconv() things, it
wouldn't make much sense to e.g. iconv() some PNG data to be "UTF-8
valid", which presumably would be the end result of something like that.
Rather that this model of assuming that a UTF-8 pattern means we can
consider everything in the repo UTF-8 in git-grep doesn't make sense. My
kwset patches *revealed* that problem in a painful way, but it was there
already.
I'm not sure what a real fix for that is. Part of it is probably 8/8 in
the series I mention below, but more generally we'd need to be more
encoding aware at a much higher callsite than "grep". So e.g. we'd know
that we match "binary" data as not-UTF-8. Now we just throw arbitrary
bytes around and hope something sticks.
> If we're already deciding to paper over things, I'd much rather prefer
> the simpler patch, i.e. Carlo's.
As I noted upthread PCRE's own docs promise undefined behavior and fire
and brimstone if that patch is applied. Those last two not
guaranteed. So we need another solution.
I've submitted
https://public-inbox.org/git/20190726150818.6373-1-avarab@gmail.com/
just now. See what you think about it.
next prev parent reply other threads:[~2019-07-26 15:15 UTC|newest]
Thread overview: 26+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-07-21 18:31 [PATCH] grep: skip UTF8 checks explicitally Carlo Marcelo Arenas Belón
2019-07-21 18:34 ` Eric Sunshine
2019-07-22 11:55 ` Johannes Schindelin
2019-07-22 14:43 ` [PATCH] grep: skip UTF8 checks explicitly Carlo Marcelo Arenas Belón
2019-07-24 2:10 ` Junio C Hamano
2019-07-24 10:50 ` Johannes Schindelin
2019-07-24 16:08 ` Junio C Hamano
2019-08-28 14:54 ` [PATCH v2] " Carlo Marcelo Arenas Belón
2019-08-28 16:57 ` Carlo Arenas
2019-09-09 15:07 ` Carlo Arenas
2019-09-09 18:49 ` Junio C Hamano
2019-07-22 19:42 ` [PATCH] grep: skip UTF8 checks explicitally Ævar Arnfjörð Bjarmason
2019-07-23 3:50 ` Carlo Arenas
2019-07-23 12:46 ` Johannes Schindelin
2019-07-24 1:47 ` Carlo Arenas
2019-07-24 10:47 ` Johannes Schindelin
2019-07-24 18:22 ` Ævar Arnfjörð Bjarmason
2019-07-24 21:04 ` Junio C Hamano
2019-07-25 9:48 ` Johannes Schindelin
2019-07-25 13:02 ` Junio C Hamano
2019-07-25 18:22 ` Johannes Schindelin
2019-07-26 15:15 ` Ævar Arnfjörð Bjarmason [this message]
2019-07-26 15:53 ` Carlo Arenas
2019-07-26 20:05 ` Ævar Arnfjörð Bjarmason
2019-07-26 16:19 ` Junio C Hamano
2019-07-26 19:40 ` Ævar Arnfjörð Bjarmason
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