Re: [PATCH] grep: skip UTF8 checks explicitly

[Johannes Schindelin <Johannes.Schindelin@gmx.de>]

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Hi Junio,

On Tue, 23 Jul 2019, Junio C Hamano wrote:

> Carlo Marcelo Arenas Belón  <carenas@gmail.com> writes:
>
> > Usually PCRE is compiled with JIT support, and therefore the code
> > path used includes calling pcre2_jit_match (for PCRE2), that ignores
> > invalid UTF-8 in the corpus.
> >
> > Make that option explicit so it can be also used when JIT is not
> > enabled and pcre2_match is called instead, preventing `git grep`
> > to abort when hitting the first binary blob in a fixed match
> > after ed0479ce3d ("Merge branch 'ab/no-kwset' into next", 2019-07-15)
> >
> > Reviewed-by: Johannes Schindelin <Johannes.Schindelin@gmx.de>
> > Signed-off-by: Carlo Marcelo Arenas Belón <carenas@gmail.com>
> > ---
> > V2: spelling fixes from Eric Sunshine
>
> Good.  I was expecting fallouts like this from our recent push to
> aggressively use pcre and that was why I merged ab/no-kwset before
> I felt comfortable, so that we can have longer exposure.  It seems
> to be paying off.

I agree: it pays off quite nicely.

> So with JIT, PCRE_NO_UTF8_CHECK is on by default, but without, we
> need to give the option explicitly, and because it is on by default
> in the JIT case, it would not hurt to explicitly pass it?
>
> That makes perfect sense to me.

My reading of the situation is slightly different. I think
PCRE_NO_UTF8_CHECK is off by default, but it only makes a difference in
the non-JIT'ed code path. Since we use PCRE2's JIT when possible
(because it leads to a quite nice performance improvement), we usually
don't see those warnings. Carlo's patch makes the non-JIT'ed code path
behave the same as our preferred code path.

Thanks,
Dscho

>
> >  grep.c | 4 ++--
> >  1 file changed, 2 insertions(+), 2 deletions(-)
> >
> > diff --git a/grep.c b/grep.c
> > index fc0ed73ef3..146093f590 100644
> > --- a/grep.c
> > +++ b/grep.c
> > @@ -409,7 +409,7 @@ static void compile_pcre1_regexp(struct grep_pat *p, const struct grep_opt *opt)
> >  static int pcre1match(struct grep_pat *p, const char *line, const char *eol,
> >  		regmatch_t *match, int eflags)
> >  {
> > -	int ovector[30], ret, flags = 0;
> > +	int ovector[30], ret, flags = PCRE_NO_UTF8_CHECK;
> >
> >  	if (eflags & REG_NOTBOL)
> >  		flags |= PCRE_NOTBOL;
> > @@ -554,7 +554,7 @@ static void compile_pcre2_pattern(struct grep_pat *p, const struct grep_opt *opt
> >  static int pcre2match(struct grep_pat *p, const char *line, const char *eol,
> >  		regmatch_t *match, int eflags)
> >  {
> > -	int ret, flags = 0;
> > +	int ret, flags = PCRE2_NO_UTF_CHECK;
> >  	PCRE2_SIZE *ovector;
> >  	PCRE2_UCHAR errbuf[256];
>