Re: [PATCH v7] read-cache: force_verify_index_checksum

From: Junio C Hamano <gitster@pobox.com>
Date: Apr 25, 2017, 02:10 UTC
Message-ID: <xmqqk269xmmq.fsf@gitster.mtv.corp.google.com>
In-Reply-To: <8bde0b54-c0f6-364d-1f08-ce5207eb6c86@jeffhostetler.com>

Jeff Hostetler <git@jeffhostetler.com> writes:

Show 17 quoted lines

>>> +test_expect_success 'detect corrupt index file in fsck' '
>>> +    cp .git/index .git/index.backup &&
>>> +    test_when_finished "mv .git/index.backup .git/index" &&
>>> +    echo zzzzzzzz >zzzzzzzz &&
>>> +    git add zzzzzzzz &&
>>> +    sed -e "s/zzzzzzzz/yyyyyyyy/" .git/index >.git/index.yyy &&
>>
>> sed on a binary file? Sooner or later we are going to run into
>> portability issues.
>
> In v5 of this patch series I used "perl" and it was suggested that I
> use "sed" instead.
> It doesn't matter to me which we use.  My testing showed that it was
> safe, but that
> was only Linux.
>
> Does the mailing list have a preference for this ?

Instead of munging pathnames z* to y*, I'd prefer to see the actual checksum bytes at the end replaced in the index file. After all that is what this test really cares about, and it ensures that the failure detected is due to checksum mismatch.

Show 11 quoted lines

>>> +    mv .git/index.yyy .git/index &&
>>> +    # Confirm that fsck detects invalid checksum
>>> +    test_must_fail git fsck --cache &&
>>
>> You should ensure that this failure is really because of an invalid
>> checksum. The failure could also be due to an extra LF at the end
>> that sed inserted, no?
>
> I suppose we could, but I'm tempted to wait on that for now.
>
> Jeff