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From: Jeff King <peff@peff.net>
To: Derrick Stolee <stolee@gmail.com>
Cc: "Ævar Arnfjörð Bjarmason" <avarab@gmail.com>,
	git@vger.kernel.org, "Junio C Hamano" <gitster@pobox.com>,
	"SZEDER Gábor" <szeder.dev@gmail.com>,
	"Eric Sunshine" <sunshine@sunshineco.com>,
	"Ramsay Jones" <ramsay@ramsayjones.plus.com>
Subject: Re: [PATCH v3 4/8] commit-graph: don't early exit(1) on e.g. "git status"
Date: Wed, 1 May 2019 14:31:08 -0400	[thread overview]
Message-ID: <20190501183108.GE4109@sigill.intra.peff.net> (raw)
In-Reply-To: <3518ad3e-bc4a-c2c3-d4bd-c87f9e828b1c@gmail.com>

On Mon, Apr 29, 2019 at 08:48:51AM -0400, Derrick Stolee wrote:

> Q: How should we handle a detectably-invalid commit-graph?
> 
> I think most of your patches have done a good job so far of detecting
> an invalid header, and responding by ignoring the commit-graph. This case
> of a detectable error in the chunk data itself is not something we can
> check on the first load without serious performance issues.
> 
> I hope we can decide on a good solution.

I think it's OK to die() unceremoniously in these cases. We already have
similar behavior when dealing with packfiles. While we try to just
return an error for bit-flips in data (so we can try finding the object
elsewhere), if there are things like nonsensical file offsets, we
generally just give up.

So I think it makes sense to start with the _safe_ thing, which is just
giving up on the operation and informing the user. If somebody wants to
then loosen things up on a case by case basis (after seeing that it
wouldn't produce incorrect results to do so), that can be future work.

For the commit-graph, though, and given that we're talking about file
corruption, I don't know that it's even worth the effort. The solution
is basically always going to be "delete the commit-graph file and
regenerate it". It's perhaps slightly inconvenient compared to falling
back, but this just isn't something we'd expect to happen often.

-Peff

  parent reply	other threads:[~2019-05-01 18:31 UTC|newest]

Thread overview: 36+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2019-02-21 22:37 [PATCH 0/8] commit-graph: segfault & other fixes for broken graphs Ævar Arnfjörð Bjarmason
2019-02-21 22:37 ` [PATCH 1/8] commit-graph tests: split up corrupt_graph_and_verify() Ævar Arnfjörð Bjarmason
2019-02-21 22:37 ` [PATCH 2/8] commit-graph tests: test a graph that's too small Ævar Arnfjörð Bjarmason
2019-02-21 22:37 ` [PATCH 3/8] commit-graph: fix segfault on e.g. "git status" Ævar Arnfjörð Bjarmason
2019-02-21 22:37 ` [PATCH 4/8] commit-graph: don't early exit(1) " Ævar Arnfjörð Bjarmason
2019-02-21 22:37 ` [PATCH 5/8] commit-graph: don't pass filename to load_commit_graph_one_fd_st() Ævar Arnfjörð Bjarmason
2019-02-21 22:37 ` [PATCH 6/8] commit-graph verify: detect inability to read the graph Ævar Arnfjörð Bjarmason
2019-02-21 23:15   ` SZEDER Gábor
2019-02-21 22:37 ` [PATCH 7/8] commit-graph write: don't die if the existing graph is corrupt Ævar Arnfjörð Bjarmason
2019-02-22 23:13   ` Junio C Hamano
2019-02-23  9:29     ` Eric Sunshine
2019-02-21 22:37 ` [PATCH 8/8] commit-graph: improve & i18n error messages Ævar Arnfjörð Bjarmason
2019-03-14 21:47 ` [PATCH v2 0/8] commit-graph: segfault & other fixes for broken graphs Ævar Arnfjörð Bjarmason
2019-03-15  7:47   ` Eric Sunshine
2019-03-15 10:39     ` Ævar Arnfjörð Bjarmason
2019-03-25 12:08   ` [PATCH v3 " Ævar Arnfjörð Bjarmason
2019-03-25 12:08   ` [PATCH v3 1/8] commit-graph tests: split up corrupt_graph_and_verify() Ævar Arnfjörð Bjarmason
2019-03-25 12:08   ` [PATCH v3 2/8] commit-graph tests: test a graph that's too small Ævar Arnfjörð Bjarmason
2019-03-25 12:08   ` [PATCH v3 3/8] commit-graph: fix segfault on e.g. "git status" Ævar Arnfjörð Bjarmason
2019-03-25 12:08   ` [PATCH v3 4/8] commit-graph: don't early exit(1) " Ævar Arnfjörð Bjarmason
2019-04-27 13:06     ` Ævar Arnfjörð Bjarmason
2019-04-29 12:48       ` Derrick Stolee
2019-04-29 14:30         ` Ævar Arnfjörð Bjarmason
2019-05-01 18:31         ` Jeff King [this message]
2019-03-25 12:08   ` [PATCH v3 5/8] commit-graph: don't pass filename to load_commit_graph_one_fd_st() Ævar Arnfjörð Bjarmason
2019-03-25 12:08   ` [PATCH v3 6/8] commit-graph verify: detect inability to read the graph Ævar Arnfjörð Bjarmason
2019-03-25 12:08   ` [PATCH v3 7/8] commit-graph write: don't die if the existing graph is corrupt Ævar Arnfjörð Bjarmason
2019-03-25 12:08   ` [PATCH v3 8/8] commit-graph: improve & i18n error messages Ævar Arnfjörð Bjarmason
2019-03-14 21:47 ` [PATCH v2 1/8] commit-graph tests: split up corrupt_graph_and_verify() Ævar Arnfjörð Bjarmason
2019-03-14 21:47 ` [PATCH v2 2/8] commit-graph tests: test a graph that's too small Ævar Arnfjörð Bjarmason
2019-03-14 21:47 ` [PATCH v2 3/8] commit-graph: fix segfault on e.g. "git status" Ævar Arnfjörð Bjarmason
2019-03-14 21:47 ` [PATCH v2 4/8] commit-graph: don't early exit(1) " Ævar Arnfjörð Bjarmason
2019-03-14 21:47 ` [PATCH v2 5/8] commit-graph: don't pass filename to load_commit_graph_one_fd_st() Ævar Arnfjörð Bjarmason
2019-03-14 21:47 ` [PATCH v2 6/8] commit-graph verify: detect inability to read the graph Ævar Arnfjörð Bjarmason
2019-03-14 21:47 ` [PATCH v2 7/8] commit-graph write: don't die if the existing graph is corrupt Ævar Arnfjörð Bjarmason
2019-03-14 21:47 ` [PATCH v2 8/8] commit-graph: improve & i18n error messages Ævar Arnfjörð Bjarmason

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