From: Tzvetan Mikov <tmikov@gmail.com>
Date: Mon, 03 Nov 2014 22:09:35 GMT
Subject: Re: [PATCH] line-log: fix crash when --first-parent is used
Message-ID: <CACt9tMj2GBWC6yRpfKXUk1hnh2ZyBqoV5HDmL0cjfxCiawHT=g@mail.gmail.com>
In-Reply-To: <xmqqoasoq9vh.fsf@gitster.dls.corp.google.com>

On Mon, Nov 3, 2014 at 12:58 PM, Junio C Hamano <gitster@pobox.com> wrote:

>> line-log tries to access all parents of a commit, but only the first
>> parent has been loaded if "--first-parent" is specified, resulting
>> in a crash.
>>
>> Limit the number of parents to one if "--first-parent" is specified.
>>

> [...]
> Tzvetan, can we have a test for this one?

Here is a sequence of commands to reproduce the crash:

git init
echo "1" > a.txt && git add a.txt && git commit -m "a"
git checkout -b branch
echo "2" > b.txt && git add b.txt && git commit -m "b"
git checkout master
git merge branch --no-ff -m "merge"
git log --first-parent -L 1,1:a.txt

I am not sure whether you have a requirement for a formal test
included with the patch, but if there is one, I am happy to
rework it.

This is a very simple fix for the crash, though possibly
a "real" comprehensive fix may be needed. I am not sure.
The real cause is that with "--first-parent" some commit
objects are never loaded from disk but may still be accessed.

(sorry about my formatting - have to use GMail)

regards,
Tzvetan