From: Bagas Sanjaya <bagasdotme@gmail.com>
Date: Thu, 24 Jun 2021 04:22:47 GMT
Subject: Re: [PATCH 4/4] midx: report checksum mismatches during 'verify'
Message-ID: <dab8eb4a-3e8e-ea3f-20ba-5164655841f2@gmail.com>
In-Reply-To: <94e9de44e3b52513c5ab48aecd74f809dc34cbe3.1624473543.git.me@ttaylorr.com>

On 24/06/21 01.39, Taylor Blau wrote:
> But it does not check that the file's trailing checksum matches the data
> that it records. So, if an on-disk corruption happened to occur in the
> final few bytes (and all other data was recorded correctly), we would:
> 
>    - get a clean result from 'git multi-pack-index verify', but
>    - be unable to reuse the existing MIDX when writing a new one (since
>      we now check for checksum mismatches before reusing a MIDX)
> 
> Teach the 'verify' sub-command to recognize corruption in the checksum
> by calling midx_checksum_valid().
...
> +	if (!midx_checksum_valid(m))
> +		midx_report(_("incorrect checksum"));
> +
...
> +test_expect_success 'verify incorrect checksum' '
> +	pos=$(($(wc -c <$objdir/pack/multi-pack-index) - 1)) &&
> +	corrupt_midx_and_verify $pos "\377" $objdir "incorrect checksum"
> +'
> +

We're in the context of checksum mismatches because of on-disk 
corruption, so why didn't the message say "incorrect checksum, possibly 
corrupt"?

-- 
An old man doll... just what I always wanted! - Clara