From: Jeff King <peff@peff.net>
To: Thomas Gummerer <t.gummerer@gmail.com>
Cc: Jonathan Nieder <jrnieder@gmail.com>,
git@vger.kernel.org, Lars Schneider <larsxschneider@gmail.com>
Subject: lstat-ing delayed-filter output, was Re: playing with MSan
Date: Wed, 4 Oct 2017 23:46:32 -0400 [thread overview]
Message-ID: <20171005034632.kzsspk7wsuk23kf2@sigill.intra.peff.net> (raw)
In-Reply-To: <20171004193005.GD30301@hank>
On Wed, Oct 04, 2017 at 08:30:05PM +0100, Thomas Gummerer wrote:
> > So I dunno. This approach is a _lot_ more convenient than trying to
> > rebuild all the dependencies from scratch, and it runs way faster than
> > valgrind. It did find the cases that led to the patches in this
> > series, and at least one more: if the lstat() at the end of
> > entry.c:write_entry() fails, we write nonsense into the cache_entry.
>
> Yeah valgrind found that one too, as I tried (and apparently failed :))
> to explain in the cover letter. I just haven't found the time yet to
> actually try and go fix that one.
No, I just have poor memory. :)
The obvious fix is that we should check the return value of `lstat`, but
the bigger question is why and when that would fail.
The case triggered by t0021 is using the new "delayed" filter mechanism.
So at the time that write_entry() finishes, we don't actually have the
file in the filesystem. I think we need to recognize that we got delayed
and didn't actually check anything out, and skip that whole "if
(state->refresh_cache)" block. It's not clear to me, though, how we tell
the difference between the delayed and normal cases in that function.
But I think this lstat could also fail if we are checking out and
somebody else racily deletes our file. This is presumably sufficiently
rare that I actually wonder if we should just bail with an error, so
that the user knows something funny is going on.
+cc Lars for thoughts no the delayed-filter case.
-Peff
next prev parent reply other threads:[~2017-10-05 3:46 UTC|newest]
Thread overview: 30+ messages / expand[flat|nested] mbox.gz Atom feed top
2017-10-03 19:57 [PATCH 0/3] fixes for running the test suite with --valgrind Thomas Gummerer
2017-10-03 19:57 ` [PATCH 1/3] path.c: fix uninitialized memory access Thomas Gummerer
2017-10-03 22:45 ` Jonathan Nieder
2017-10-03 23:30 ` Jeff King
2017-10-03 23:37 ` Jonathan Nieder
2017-10-04 4:47 ` Junio C Hamano
2017-10-04 5:21 ` Jeff King
2017-10-04 19:22 ` Thomas Gummerer
2017-10-04 19:36 ` Jonathan Nieder
2017-10-03 19:57 ` [PATCH 2/3] http-push: fix construction of hex value from path Thomas Gummerer
2017-10-03 22:53 ` Jonathan Nieder
2017-10-03 23:36 ` Jeff King
2017-10-04 4:48 ` Junio C Hamano
2017-10-04 5:20 ` Junio C Hamano
2017-10-04 5:26 ` Jeff King
2017-10-04 6:26 ` Junio C Hamano
2017-10-03 19:57 ` [PATCH 3/3] sub-process: allocate argv on the heap Thomas Gummerer
2017-10-03 20:24 ` Johannes Sixt
2017-10-04 4:59 ` Junio C Hamano
2017-10-04 5:32 ` Jeff King
2017-10-04 5:58 ` Johannes Sixt
2017-10-04 19:31 ` Thomas Gummerer
2017-10-03 20:25 ` Stefan Beller
2017-10-03 23:41 ` [PATCH 0/3] fixes for running the test suite with --valgrind Jeff King
2017-10-03 23:50 ` Jonathan Nieder
2017-10-03 23:54 ` Jeff King
2017-10-04 10:19 ` playing with MSan, was " Jeff King
2017-10-04 19:30 ` Thomas Gummerer
2017-10-05 3:46 ` Jeff King [this message]
2017-10-05 10:47 ` lstat-ing delayed-filter output, was Re: playing with MSan Lars Schneider
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