GNU bug report logs - #17066
a DFA state which is built previously may be re-built in non-UTF8 locales

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Message #5 received at submit <at> debbugs.gnu.org (full text, mbox):

From: Norihiro Tanaka <noritnk <at> kcn.ne.jp>
To: submit <at> debbugs.gnu.org
Subject: a DFA state which is built previously may be re-built in non-UTF8
 locales
Date: Sat, 22 Mar 2014 15:59:11 +0900

[Message part 1 (text/plain, inline)]

Package: grep

When don't pass backref parameter to dfaexec(), a DFA state which is built
previously may be re-built.

In non-UTF8 locales, when reach a state which mbps aren't empty, exit
main loop and call build_state() in dfa.c, even if the state has been
already built.

That will cause increase of processing time, and waste of a lot of
memories.

Fortunately, grep program doesn't pass the code in dfa.c unless
mblen_buf overflows, since backref parameter is specified when dfaexec()
is called with large buffer.

Norihiro

[patch.txt (text/plain, attachment)]

Message #10 received at 17066 <at> debbugs.gnu.org (full text, mbox):

From: Paolo Bonzini <bonzini <at> gnu.org>
To: Norihiro Tanaka <noritnk <at> kcn.ne.jp>, 17066 <at> debbugs.gnu.org
Subject: Re: bug#17066: a DFA state which is built previously may be re-built
 in non-UTF8 locales
Date: Tue, 01 Apr 2014 10:47:27 +0200

Il 22/03/2014 07:59, Norihiro Tanaka ha scritto:
>
> From fba7984fa2a5baff18e1b48611c3d7fb3701255b Mon Sep 17 00:00:00 2001
> From: Norihiro Tanaka <noritnk <at> kcn.ne.jp>
> Date: Sat, 22 Mar 2014 15:11:52 +0900
> Subject: [PATCH] grep: avoid to re-build a state built previously.
>
> * src/dfa.c (dfaexec): avoid to re-build a state built previously.
> ---
>  src/dfa.c | 3 ++-
>  1 file changed, 2 insertions(+), 1 deletion(-)
>
> diff --git a/src/dfa.c b/src/dfa.c
> index 5e60cd5..8261849 100644
> --- a/src/dfa.c
> +++ b/src/dfa.c
> @@ -3501,7 +3501,8 @@ dfaexec (struct dfa *d, char const *begin, char *end,
>
>        if (s >= 0)
>          {
> -          build_state (s, d);
> +          if (!d->trans[s])
> +            build_state (s, d);
>            trans = d->trans;
>            continue;
>          }
> -- 1.9.1

Thanks, I'll apply this patch.

Paolo

Message #15 received at 17066-done <at> debbugs.gnu.org (full text, mbox):

From: Paul Eggert <eggert <at> cs.ucla.edu>
To: Paolo Bonzini <bonzini <at> gnu.org>, Norihiro Tanaka <noritnk <at> kcn.ne.jp>, 
 17066-done <at> debbugs.gnu.org
Subject: Re: bug#17066: a DFA state which is built previously may be re-built
 in non-UTF8 locales
Date: Tue, 01 Apr 2014 22:25:40 -0700

Paolo Bonzini wrote:
> Thanks, I'll apply this patch.

Thanks, closing this bug report as done.

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