From: Junio C Hamano <gitster@pobox.com>
To: "René Scharfe" <l.s.r@web.de>
Cc: Vegard Nossum <vegard.nossum@oracle.com>,
git@vger.kernel.org,
Christian Couder <christian.couder@gmail.com>,
Michal Zalewski <lcamtuf@google.com>
Subject: Re: [PATCH 2/2] apply: handle assertion failure gracefully
Date: Mon, 27 Feb 2017 14:33:15 -0800 [thread overview]
Message-ID: <xmqq1sujnu1g.fsf@gitster.mtv.corp.google.com> (raw)
In-Reply-To: <f191e3a8-a55b-7030-ebbb-3f46c74fdc94@web.de> ("René Scharfe"'s message of "Mon, 27 Feb 2017 23:18:03 +0100")
René Scharfe <l.s.r@web.de> writes:
> Am 27.02.2017 um 21:04 schrieb Junio C Hamano:
>> René Scharfe <l.s.r@web.de> writes:
>>
>>>> diff --git a/apply.c b/apply.c
>>>> index cbf7cc7f2..9219d2737 100644
>>>> --- a/apply.c
>>>> +++ b/apply.c
>>>> @@ -3652,7 +3652,6 @@ static int check_preimage(struct apply_state *state,
>>>> if (!old_name)
>>>> return 0;
>>>>
>>>> - assert(patch->is_new <= 0);
>>>
>>> 5c47f4c6 (builtin-apply: accept patch to an empty file) added that
>>> line. Its intent was to handle diffs that contain an old name even for
>>> a file that's created. Citing from its commit message: "When we
>>> cannot be sure by parsing the patch that it is not a creation patch,
>>> we shouldn't complain when if there is no such a file." Why not stop
>>> complaining also in case we happen to know for sure that it's a
>>> creation patch? I.e., why not replace the assert() with:
>>>
>>> if (patch->is_new == 1)
>>> goto is_new;
>>>
>>>> previous = previous_patch(state, patch, &status);
>>
>> When the caller does know is_new is true, old_name must be made/left
>> NULL. That is the invariant this assert is checking to catch an
>> error in the calling code.
>
> There are some places in apply.c that set ->is_new to 1, but none of
> them set ->old_name to NULL at the same time.
I thought all of these are flipping ->is_new that used to be -1
(unknown) to (now we know it is new), and sets only new_name without
doing anything to old_name, because they know originally both names
are set to NULL.
> Having to keep these two members in sync sounds iffy anyway. Perhaps
> accessors can help, e.g. a setter which frees old_name when is_new is
> set to 1, or a getter which returns NULL for old_name if is_new is 1.
Definitely, the setter would make it harder to make the mistake.
next prev parent reply other threads:[~2017-02-27 22:35 UTC|newest]
Thread overview: 19+ messages / expand[flat|nested] mbox.gz Atom feed top
2017-02-25 10:13 [PATCH 1/2] apply: guard against renames of non-existant empty files Vegard Nossum
2017-02-25 10:13 ` [PATCH 2/2] apply: handle assertion failure gracefully Vegard Nossum
2017-02-25 21:21 ` René Scharfe
2017-02-27 20:04 ` Junio C Hamano
2017-02-27 22:18 ` René Scharfe
2017-02-27 22:33 ` Junio C Hamano [this message]
2017-02-28 10:50 ` René Scharfe
2017-06-27 17:03 ` René Scharfe
2017-06-27 18:08 ` Junio C Hamano
2017-06-27 20:20 ` René Scharfe
2017-06-27 21:39 ` Junio C Hamano
2017-06-27 17:03 ` René Scharfe
2017-02-25 11:59 ` [PATCH 1/2] apply: guard against renames of non-existant empty files Philip Oakley
2017-02-25 12:06 ` Vegard Nossum
2017-02-25 12:47 ` Philip Oakley
2017-02-25 20:51 ` René Scharfe
2017-02-27 20:10 ` Junio C Hamano
2017-02-27 22:18 ` René Scharfe
2017-06-27 17:03 ` René Scharfe
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