Re: [PATCH v4 3/3] regex: use regexec_buf()

From: Junio C Hamano <gitster@pobox.com>
Date: Sep 21, 2016, 20:09 UTC
Message-ID: <xmqqintp6mm8.fsf@gitster.mtv.corp.google.com>
In-Reply-To: <xmqqmvj16p06.fsf@gitster.mtv.corp.google.com>

Junio C Hamano <gitster@pobox.com> writes:

Show 13 quoted lines

> Johannes Schindelin <johannes.schindelin@gmx.de> writes:
>
>> The new regexec_buf() function operates on buffers with an explicitly
>> specified length, rather than NUL-terminated strings.
>>
>> We need to use this function whenever the buffer we want to pass to
>> regexec() may have been mmap()ed (and is hence not NUL-terminated).
>>
>> Note: the original motivation for this patch was to fix a bug where
>> `git diff -G <regex>` would crash. This patch converts more callers,
>> though, some of which explicitly allocated and constructed
>> NUL-terminated strings (or worse: modified read-only buffers to insert
>> NULs).

Also, I think there is nobody that modified read-only buffer. diffgrep_consume() does say "Yuck -- line ought to be const", but its "line" parameter is actually a non-const exactly for this yuckiness (iow, it knew what it was doing).

Perhaps like so?

    regex: use regexec_buf()
    
    The new regexec_buf() function operates on buffers with an explicitly
    specified length, rather than NUL-terminated strings.
    
    We need to use this function whenever the buffer we want to pass to
    regexec(3) may have been mmap(2)ed (and is hence not NUL-terminated).
    
    Note: the original motivation for this patch was to fix a bug where
    `git diff -G <regex>` would crash. This patch converts more callers,
    though, some of which allocated to construct NUL-terminated strings,
    or worse, modified buffers to temporarily insert NULs while calling
    regexec(3).  By converting them to use regexec_buf() they have become
    much cleaner.
    
    Signed-off-by: Johannes Schindelin <johannes.schindelin@gmx.de>
    Signed-off-by: Junio C Hamano <gitster@pobox.com>

The patch text looked good to me.

Thanks.