From: Jeff King <peff@peff.net>
To: Duy Nguyen <pclouds@gmail.com>
Cc: "Junio C Hamano" <gitster@pobox.com>,
"Ævar Arnfjörð Bjarmason" <avarab@gmail.com>,
"Van Oostenryck Luc" <luc.vanoostenryck@gmail.com>,
"Git Mailing List" <git@vger.kernel.org>,
"Kevin Willford" <kewillf@microsoft.com>
Subject: Re: [BUG] index corruption with git commit -p
Date: Tue, 4 Sep 2018 12:38:08 -0400 [thread overview]
Message-ID: <20180904163807.GA23572@sigill.intra.peff.net> (raw)
In-Reply-To: <CACsJy8AuWKxAdETaqYmcSY2VeLeWFyjnSYrK4GJeyG5ecv3OcA@mail.gmail.com>
On Tue, Sep 04, 2018 at 06:13:36PM +0200, Duy Nguyen wrote:
> > > Doh, of course. I even thought about this issue and dug all the way into
> > > reopen_lock_file(), but for some reason temporarily forgot that O_WRONLY
> > > does not imply O_TRUNC.
> > >
> > > Arguably this should be the default for reopen_lockfile(), as getting a
> > > write pointer into an existing file is not ever going to be useful for
> > > the way Git uses lockfiles. Opening with O_APPEND could conceivably be
> > > useful, but it's pretty unlikely (and certainly not helpful here, and
> > > this is the only caller). Alternatively, the function should just take
> > > open(2) flags.
> > >
> > > At any rate, I think this perfectly explains the behavior we're seeing.
> >
> > Thanks all for digging this down (I am a bit jealous to see that I
> > seem to have missed all this fun over the weekend X-<).
>
> And just to be clear I'm looking forward to a patch from Jeff to fix
> this since he clearly put more thoughts on this than me. With commit.c
> being the only user of reopen_lock_file() I guess it's even ok to just
> stick O_TRUNC in there and worry about O_APPEND when a new caller
> needs that.
That's the way I'm leaning to. The fix is obviously a one-liner, but I
was hoping to construct a minimal test case. I just haven't gotten
around to it yet.
The bug is ancient, so I don't think it's important for v2.19.
-Peff
next prev parent reply other threads:[~2018-09-04 16:38 UTC|newest]
Thread overview: 19+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-09-01 21:41 [BUG] index corruption with git commit -p Luc Van Oostenryck
2018-09-01 22:17 ` Ævar Arnfjörð Bjarmason
2018-09-02 5:08 ` Jeff King
2018-09-02 7:12 ` Duy Nguyen
2018-09-02 7:24 ` Jeff King
2018-09-02 7:53 ` Luc Van Oostenryck
2018-09-02 8:02 ` Jeff King
2018-09-04 15:57 ` Junio C Hamano
2018-09-04 16:13 ` Duy Nguyen
2018-09-04 16:38 ` Jeff King [this message]
2018-09-04 23:36 ` [PATCH] reopen_tempfile(): truncate opened file Jeff King
2018-09-05 15:27 ` Duy Nguyen
2018-09-05 15:35 ` Jeff King
2018-09-05 15:39 ` Duy Nguyen
2018-09-05 15:48 ` Jeff King
2018-09-05 16:54 ` Junio C Hamano
2018-09-05 16:56 ` Jeff King
2018-09-05 17:01 ` Junio C Hamano
2018-09-05 18:48 ` Luc Van Oostenryck
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