Subject: bug#25336: closed (Re: bug#25336:)

From: [email-masked] (GNU bug Tracking System)
Date: Mon, 02 Jan 2017 18:31:02 +0000

Your bug report

#25336: 

which was filed against the grep package, has been closed.

The explanation is attached below, along with your original report.
If you require more details, please reply to [email-masked].

-- 
25336: http://debbugs.gnu.org/cgi/bugreport.cgi?bug=25336
GNU Bug Tracking System
Contact [email-masked] with problems

Subject: Re: bug#25336:
From: Paul Eggert <[email-masked]>
To: Zepp Lu <[email-masked]>, [email-masked]
Date: Mon, 2 Jan 2017 10:30:32 -0800
List-Id: <debbugs-submit.debbugs.gnu.org>

Zepp Lu wrote:

> $ printf '\x53\xef' | grep -aoP '\x53\xef'
> (no output, returns 1)
> $ printf '\x53\xc3\xaf' | grep -aoP '\x53\xef'
> Sï
> $ printf '\x53\xc3\xef' | grep -aoP '\x53\xef'
> (no output, returns 1)

I don't see a bug here. PCRE patterns like \xef match code points, not bytes, so 
the PCRE notation differs from the shell printf notation. If your locale uses 
UTF-8, the PCRE pattern \xef matches the Unicode character U+00EF LATIN SMALL 
LETTER I WITH DIAERESIS, which is represented by the byte pair C3 AF.

If you want \xef to match a single byte, run grep in a single-byte locale, e.g., 
set LC_ALL=C in the environment.

> grep (version 2.12-2) provided by Debian works just fine.

Actually, it's buggy in this area. Sometimes it can dump core.

From: Zepp Lu <[email-masked]>
To: [email-masked]
Date: Mon, 2 Jan 2017 21:22:59 +0800
List-Id: <debbugs-submit.debbugs.gnu.org>

OS: Archlinux
grep version: 2.27-1

Bug description: grep behaves weirdly when searching hex values.

How to reproduce:
$ printf '\x53\xef' | grep -aoP '\x53\xef'
(no output, returns 1)
$ printf '\x53\xc3\xaf' | grep -aoP '\x53\xef'
Sï
$ printf '\x53\xc3\xef' | grep -aoP '\x53\xef'
(no output, returns 1)

grep (version 2.12-2) provided by Debian works just fine.