From: Junio C Hamano <gitster@pobox.com>
Date: Wed, 21 Sep 2016 19:17:56 GMT
Subject: Re: [PATCH v4 2/3] regex: add regexec_buf() that can work on a non NUL-terminated string
Message-ID: <xmqqtwd96p0b.fsf@gitster.mtv.corp.google.com>
In-Reply-To: <270cea11c4d8bfb332a6c014a11673b7f4666ee4.1474482164.git.johannes.schindelin@gmx.de>

Johannes Schindelin <johannes.schindelin@gmx.de> writes:

> ...
> Happily, there is an extension to regexec() introduced by the NetBSD
> project and present in all major regex implementation including
> Linux', MacOSX' and the one Git includes in compat/regex/: by using
> the (non-POSIX) REG_STARTEND flag, it is possible to tell the
> regexec() function that it should only look at the offsets between
> pmatch[0].rm_so and pmatch[0].rm_eo.
>
> That is exactly what we need.

Wonderful.

> Since support for REG_STARTEND is so widespread by now, let's just
> introduce a helper function that uses it, and fall back to allocating
> and constructing a NUL-terminated when REG_STARTEND is not available.

I'd somehow reword the last paragraph here, though ;-)

    Since support for REG_STARTEND is so widespread by now, let's just
    introduce a helper function that always uses it, and tell people
    on a platform whose regex library does not support it to use the
    one from our compat/regex/ directory.

The patch itself looks very sane.  Thanks.