From: Derrick Stolee <stolee@gmail.com>
Date: Thu, 26 Dec 2019 14:50:09 GMT
Subject: Re: [PATCH 10/20] t5319: make test work with SHA-256
Message-ID: <54d80d36-f9b9-1c92-faf0-41bbcbe0a133@gmail.com>
In-Reply-To: <20191221194936.1346664-11-sandals@crustytoothpaste.net>

On 12/21/2019 2:49 PM, brian m. carlson wrote:
> This test corrupts various locations in a multi-pack index to test
> various error responses.  However, these offsets differ between SHA-1
> indexes and SHA-256 indexes due to differences in object length.  Use
> test_oid to look up the correct offsets based on the algorithm.
> ---
>  t/t5319-multi-pack-index.sh | 22 ++++++++++++++++++----
>  1 file changed, 18 insertions(+), 4 deletions(-)
> 
> diff --git a/t/t5319-multi-pack-index.sh b/t/t5319-multi-pack-index.sh
> index 464bb68e89..43a7a66c9d 100755
> --- a/t/t5319-multi-pack-index.sh
> +++ b/t/t5319-multi-pack-index.sh
> @@ -28,6 +28,20 @@ midx_read_expect () {
>  	test_cmp expect actual
>  }
>  
> +test_expect_success 'setup' '
> +	test_oid_init &&
> +	test_oid_cache <<-EOF
> +	idxoff sha1:2999
> +	idxoff sha256:3739
> +
> +	packnameoff sha1:652
> +	packnameoff sha256:940
> +
> +	fanoutoff sha1:1
> +	fanoutoff sha256:3
> +	EOF
> +'
> +
>  test_expect_success 'write midx with no packs' '
>  	test_when_finished rm -f pack/multi-pack-index &&
>  	git multi-pack-index --object-dir=. write &&
> @@ -225,7 +239,7 @@ test_expect_success 'verify bad signature' '
>  		"multi-pack-index signature"
>  '
>  
> -HASH_LEN=20
> +HASH_LEN=$(test_oid rawsz)

I'm glad this was an easy update.

> +MIDX_OFFSET_OID_FANOUT=$(($MIDX_OFFSET_PACKNAMES + $(test_oid packnameoff)))
> +MIDX_BYTE_OID_FANOUT_ORDER=$((MIDX_OFFSET_OID_FANOUT + 250 * $MIDX_OID_FANOUT_WIDTH + $(test_oid fanoutoff)))

I see why these are necessary: we need to find an exact position that
causes an order check to fail. In that sense, the offsets need to match
the early bytes of a packfile name or an OID fanout value.

> @@ -387,7 +401,7 @@ test_expect_success 'force some 64-bit offsets with pack-objects' '
>  	pack64=$(git pack-objects --index-version=2,0x40 objects64/pack/test-64 <obj-list) &&
>  	idx64=objects64/pack/test-64-$pack64.idx &&
>  	chmod u+w $idx64 &&
> -	corrupt_data $idx64 2999 "\02" &&
> +	corrupt_data $idx64 $(test_oid idxoff) "\02" &&

Sorry that this was not a better-calculated value, but
your approach works well here.

Thanks,
-Stolee