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From: Derrick Stolee <stolee@gmail.com>
To: Jeff King <peff@peff.net>, Taylor Blau <me@ttaylorr.com>
Cc: "SZEDER Gábor" <szeder.dev@gmail.com>,
	git@vger.kernel.org, dstolee@microsoft.com
Subject: Re: [PATCH] t5319: corrupt more bytes of the midx checksum
Date: Tue, 16 Nov 2021 17:12:59 -0500	[thread overview]
Message-ID: <cb995591-d837-ac3d-9935-5eab1c98b4d7@gmail.com> (raw)
In-Reply-To: <YZQk6t1veegeAlYh@coredump.intra.peff.net>

On 11/16/2021 4:38 PM, Jeff King wrote:
> So very occasionally we can end up with a real 0xff byte, and the test
> fails. The most robust fix would be to read out the final byte and then
> change it to something else (e.g., adding 1 mod 256). But that's awkward
> to do in shell. Let's just blindly corrupt 10 bytes instead of 1, which
> reduces our chances of an accidental noop to 1 in 2^80.
> 
> Reported-by: SZEDER Gábor <szeder.dev@gmail.com>
> Signed-off-by: Jeff King <peff@peff.net>
> ---
>  t/t5319-multi-pack-index.sh | 6 ++++--
>  1 file changed, 4 insertions(+), 2 deletions(-)
> 
> diff --git a/t/t5319-multi-pack-index.sh b/t/t5319-multi-pack-index.sh
> index 3f69e43178..a612e44547 100755
> --- a/t/t5319-multi-pack-index.sh
> +++ b/t/t5319-multi-pack-index.sh
> @@ -482,8 +482,10 @@ test_expect_success 'corrupt MIDX is not reused' '
>  '
>  
>  test_expect_success 'verify incorrect checksum' '
> -	pos=$(($(wc -c <$objdir/pack/multi-pack-index) - 1)) &&
> -	corrupt_midx_and_verify $pos "\377" $objdir "incorrect checksum"
> +	pos=$(($(wc -c <$objdir/pack/multi-pack-index) - 10)) &&
> +	corrupt_midx_and_verify $pos \
> +		"\377\377\377\377\377\377\377\377\377\377" \
> +		$objdir "incorrect checksum"
>  '

Thanks for taking the time to make this a patch. This approach looks
good to me.

Thanks,
-Stolee

      parent reply	other threads:[~2021-11-16 22:13 UTC|newest]

Thread overview: 16+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-06-23 18:39 [PATCH 0/4] midx: verify MIDX checksum before reusing Taylor Blau
2021-06-23 18:39 ` [PATCH 1/4] csum-file: introduce checksum_valid() Taylor Blau
2021-06-24 19:42   ` Jeff King
2021-06-23 18:39 ` [PATCH 2/4] commit-graph: rewrite to use checksum_valid() Taylor Blau
2021-06-24 19:42   ` Jeff King
2021-06-23 18:39 ` [PATCH 3/4] midx: don't reuse corrupt MIDXs when writing Taylor Blau
2021-06-24 20:00   ` Jeff King
2021-06-23 18:39 ` [PATCH 4/4] midx: report checksum mismatches during 'verify' Taylor Blau
2021-06-24  4:22   ` Bagas Sanjaya
2021-06-24 20:10   ` Jeff King
2021-11-10 23:11   ` SZEDER Gábor
2021-11-11 10:05     ` Jeff King
2021-11-16 21:10       ` Taylor Blau
2021-11-16 21:38         ` [PATCH] t5319: corrupt more bytes of the midx checksum Jeff King
2021-11-16 21:43           ` Taylor Blau
2021-11-16 22:12           ` Derrick Stolee [this message]

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