From: Jeff King <peff@peff.net>
To: Johannes Schindelin <Johannes.Schindelin@gmx.de>
Cc: git@vger.kernel.org, Junio C Hamano <gitster@pobox.com>
Subject: Re: [PATCH 2/3] diff_populate_filespec: NUL-terminate buffers
Date: Thu, 8 Sep 2016 04:22:46 -0400 [thread overview]
Message-ID: <20160908082246.saf7vlw2xgjo7jvg@sigill.intra.peff.net> (raw)
In-Reply-To: <alpine.DEB.2.20.1609080933470.129229@virtualbox>
On Thu, Sep 08, 2016 at 09:49:38AM +0200, Johannes Schindelin wrote:
> > > diff --git a/diff.c b/diff.c
> > > index 534c12e..2c5a360 100644
> > > --- a/diff.c
> > > +++ b/diff.c
> > > @@ -951,7 +951,13 @@ static int find_word_boundaries(mmfile_t *buffer,
> > > regex_t *word_regex,
> > > {
> > > if (word_regex && *begin < buffer->size) {
> > > regmatch_t match[1];
> > > - if (!regexec(word_regex, buffer->ptr + *begin, 1, match,
> > > 0)) {
> > > + int f = 0;
> > > +#ifdef REG_STARTEND
> > > + match[0].rm_so = 0;
> > > + match[0].rm_eo = *end - *begin;
> > > + f = REG_STARTEND;
> > > +#endif
> > > + if (!regexec(word_regex, buffer->ptr + *begin, 1, match,
> > > f)) {
>
> Heh. You introduced the same bug I did. Or maybe you just fetched my
> mmap-regexec branch and looked at an intermediate iteration?
I do not think I introduced anything. The quoted text is what you
sent. Which is perhaps why it has your bug. :)
> > But I much prefer this approach to copying the data just to add a NUL.
>
> I think it is not worth the burden. The only regex implementation in
> semi-widespread use that do not support REG_STARTEND seems to be musl.
>
> I'd rather not spend *so much* effort just to support an obscure platform.
> Not when the users of that obscure platform could spend that effort
> themselves. And probably won't, because we only copy data to add a NUL on
> those platforms when regexec() is called on an mmfile_t.
I'm confused about what you think I'm proposing. I was saying I _like_
something like regexec_buf() instead of copying the data. Which seems
like the simpler thing to me (and presumably to you). Or do you mean
using compat/regex to build on re_search() consistently? I do not think
that is all that complex; the question is only whether people really
want to use their own regex libraries.
Between the two options for regexec_buf(), I think you have convinced me
that REG_STARTEND is better than just using compat/regex everywhere. I
do think the fallback for platforms like musl should be "use
compat/regex" and not doing an expensive copy (which in most cases is
not even necessary).
-Peff
next prev parent reply other threads:[~2016-09-08 8:22 UTC|newest]
Thread overview: 66+ messages / expand[flat|nested] mbox.gz Atom feed top
2016-09-05 15:44 [PATCH 0/3] Fix a segfault caused by regexec() being called on mmap()ed data Johannes Schindelin
2016-09-05 15:45 ` [PATCH 1/3] Demonstrate a problem: our pickaxe code assumes NUL-terminated buffers Johannes Schindelin
2016-09-06 18:43 ` Jeff King
2016-09-08 7:53 ` Johannes Schindelin
2016-09-05 15:45 ` [PATCH 2/3] diff_populate_filespec: NUL-terminate buffers Johannes Schindelin
2016-09-06 7:06 ` Jeff King
2016-09-06 16:02 ` Johannes Schindelin
2016-09-06 18:41 ` Jeff King
2016-09-07 18:31 ` Junio C Hamano
2016-09-08 7:52 ` Johannes Schindelin
2016-09-08 7:49 ` Johannes Schindelin
2016-09-08 8:22 ` Jeff King [this message]
2016-09-08 16:57 ` Junio C Hamano
2016-09-08 18:22 ` Johannes Schindelin
2016-09-08 18:48 ` Jeff King
2016-09-05 15:45 ` [PATCH 3/3] diff_grep: add assertions verifying that the buffers are NUL-terminated Johannes Schindelin
2016-09-06 7:08 ` Jeff King
2016-09-06 16:04 ` Johannes Schindelin
2016-09-05 19:10 ` [PATCH 0/3] Fix a segfault caused by regexec() being called on mmap()ed data Junio C Hamano
2016-09-06 7:12 ` Jeff King
2016-09-06 14:06 ` Johannes Schindelin
2016-09-06 18:29 ` Jeff King
2016-09-08 7:29 ` Johannes Schindelin
2016-09-08 8:00 ` Jeff King
2016-09-09 10:09 ` Johannes Schindelin
2016-09-09 17:46 ` Junio C Hamano
2016-09-06 13:21 ` Johannes Schindelin
2016-09-06 6:58 ` Jeff King
2016-09-06 14:13 ` Johannes Schindelin
2016-09-08 7:31 ` [PATCH v2 " Johannes Schindelin
2016-09-08 7:31 ` [PATCH v2 2/3] Introduce a function to run regexec() on non-NUL-terminated buffers Johannes Schindelin
2016-09-08 8:04 ` Jeff King
2016-09-09 9:45 ` Johannes Schindelin
2016-09-09 9:59 ` Jeff King
2016-09-08 7:31 ` [PATCH v2 1/3] Demonstrate a problem: our pickaxe code assumes NUL-terminated buffers Johannes Schindelin
2016-09-08 7:31 ` [PATCH v2 3/3] Use the newly-introduced regexec_buf() function Johannes Schindelin
2016-09-08 7:54 ` Johannes Schindelin
2016-09-08 8:10 ` Jeff King
2016-09-08 8:14 ` Jeff King
2016-09-08 8:35 ` Jeff King
2016-09-08 19:06 ` Ramsay Jones
2016-09-08 19:53 ` Jeff King
2016-09-08 21:30 ` Junio C Hamano
2016-09-08 7:33 ` [PATCH v2 0/3] Fix a segfault caused by regexec() being called on mmap()ed data Johannes Schindelin
2016-09-08 8:13 ` Jeff King
2016-09-08 7:57 ` [PATCH v3 " Johannes Schindelin
2016-09-08 7:57 ` [PATCH v3 1/3] Demonstrate a problem: our pickaxe code assumes NUL-terminated buffers Johannes Schindelin
2016-09-08 7:58 ` [PATCH v3 2/3] Introduce a function to run regexec() on non-NUL-terminated buffers Johannes Schindelin
2016-09-08 17:03 ` Junio C Hamano
2016-09-08 7:59 ` [PATCH v3 3/3] Use the newly-introduced regexec_buf() function Johannes Schindelin
2016-09-08 17:09 ` Junio C Hamano
2016-09-09 9:52 ` Johannes Schindelin
2016-09-09 9:57 ` Jeff King
2016-09-09 10:41 ` Johannes Schindelin
2016-09-09 17:49 ` Junio C Hamano
2016-09-21 18:23 ` [PATCH v4 0/3] Fix a segfault caused by regexec() being called on mmap()ed data Johannes Schindelin
2016-09-21 18:23 ` [PATCH v4 1/3] regex: -G<pattern> feeds a non NUL-terminated string to regexec() and fails Johannes Schindelin
2016-09-21 18:24 ` [PATCH v4 2/3] regex: add regexec_buf() that can work on a non NUL-terminated string Johannes Schindelin
2016-09-21 19:17 ` Junio C Hamano
2016-09-22 18:38 ` Johannes Schindelin
2016-09-21 18:24 ` [PATCH v4 3/3] regex: use regexec_buf() Johannes Schindelin
2016-09-21 19:18 ` Junio C Hamano
2016-09-21 20:09 ` Junio C Hamano
2016-09-21 22:03 ` Jeff King
2016-09-25 14:01 ` Johannes Schindelin
2016-09-21 22:04 ` [PATCH v4 0/3] Fix a segfault caused by regexec() being called on mmap()ed data Jeff King
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