From: Junio C Hamano <gitster@pobox•com>
To: Jeff King <peff@peff•net>
Cc: Jorge <griffin@gmx•es>, git@vger•kernel.org
Subject: Re: Bug: .gitconfig folder
Date: Thu, 28 May 2015 10:06:43 -0700 [thread overview]
Message-ID: <xmqqbnh4iqcc.fsf@gitster.dls.corp.google.com> (raw)
In-Reply-To: <20150528075142.GB3688@peff.net> (Jeff King's message of "Thu, 28 May 2015 03:51:42 -0400")
Jeff King <peff@peff•net> writes:
> On Wed, May 27, 2015 at 03:38:12PM -0700, Junio C Hamano wrote:
>
>> The patch was meant to be a tongue-in-cheek tangent that is a vast
>> improvement for cases where we absolutely need to use mmap but does
>> not help the OP at all ;-) I do not think there is any need for the
>> config reader to read the existing file via mmap interface; just
>> open it, strbuf_read() the whole thing (and complain when it cannot)
>> and we should be ok.
>>
>> Or do we write back through the mmaped region or something?
>
> No, I think we must never do that in our code because our compat mmap
> implementation uses pread(). So all maps must be MAP_PRIVATE (and our
> compat mmap barfs if it is not).
>
> I started to go the strbuf_read() route, but it just felt so dirty to
> change the way the code works only to try to get a better error message.
Hmm. I actually thought that we long time ago updated the system to
read small loose object files via read(2) instead of mmap(2) purely
as an optimization, as mmap(2) is a bad match if you are going to
read the whole thing from the beginning to the end anyway, and the
"why not strbuf_read() the whole configuration file" was a suggestion
along that line.
But apparently we do not have such an optimization in read_object()
codepath, perhaps I was hallucinating X-<.
> ... but the config-writing code is such a tangled
> mess that I don't want to spend the time or risk the regressions.
That part I agree with. I was kinda hoping that the previous GSoC
would clean it up, but that did not happen.
prev parent reply other threads:[~2015-05-28 17:06 UTC|newest]
Thread overview: 20+ messages / expand[flat|nested] mbox.gz Atom feed top
2015-05-27 13:29 Bug: .gitconfig folder Jorge
2015-05-27 20:30 ` Junio C Hamano
2015-05-27 22:18 ` Jeff King
2015-05-27 22:24 ` Stefan Beller
2015-05-28 6:13 ` Jeff King
2015-05-27 22:38 ` Junio C Hamano
2015-05-28 7:51 ` Jeff King
2015-05-28 7:54 ` [PATCH 1/4] read-cache.c: drop PROT_WRITE from mmap of index Jeff King
2015-05-28 7:54 ` [PATCH 2/4] config.c: fix mmap leak when writing config Jeff King
2015-06-30 14:34 ` [PATCH] config.c: fix writing config files on Windows network shares Karsten Blees
2015-06-30 14:46 ` Torsten Bögershausen
2015-06-30 16:01 ` Jeff King
2015-06-30 14:52 ` Johannes Schindelin
2015-06-30 16:00 ` Jeff King
2015-05-28 7:56 ` [PATCH 3/4] config.c: avoid xmmap error messages Jeff King
2015-05-28 8:03 ` [PATCH 4/4] config.c: rewrite ENODEV into EISDIR when mmap fails Jeff King
2015-05-28 17:11 ` Junio C Hamano
2015-05-28 20:44 ` Jeff King
2015-05-28 21:11 ` Junio C Hamano
2015-05-28 17:06 ` Junio C Hamano [this message]
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