From: Dragan Simic <dsimic@manjaro.org>
Date: Fri, 05 Jan 2024 19:06:46 GMT
Subject: Re: [BUG] mv: can trigger assertion failure with three parameters (builtin/mv.c:481)
Message-ID: <7c689d58c63998e6a690207be00d3875@manjaro.org>
In-Reply-To: <xmqqil47obnw.fsf@gitster.g>

On 2024-01-05 19:52, Junio C Hamano wrote:
> "Kristoffer Haugsbakk" <code@khaugsbakk.name> writes:
> 
>> You can trigger an assertion by giving these arguments to `git mv`:
>> 
>>     <dir>/file <dir> <other dir>
>> ...
>>> What did you expect to happen? (Expected behavior)
>> 
>> A normal error message if the command is nonsensical (I don’t know; 
>> that’s
>> not the point). Also `.git/index.lock` to be cleaned up.
> 
> Good find.

Yes, thanks to Kristoffer for reporting this issue.

> Not just that, but when the command fails in the middle like this,
> it leaves the working tree in a half-updated state, i.e.
> 
>> ./bin-wrappers/git -C $dir mv $dir/a/a.txt $dir/a $dir/b
> 
> will first move a/a.txt to b/a.txt, then try to move a (actually,
> all contents of it, including a/a.txt) to b/a and finds that "the
> command is nonsensical" and aborts, and by that time, there is no
> a/a.txt (i.e. the working tree has been modified).  The failure
> should be made atomic, just like "git switch" to another branch may
> stop _without_ touching anything in the working tree when it may
> have to fail (e.g., due to a file being dirty).
> 
> Thanks for reporting, Kristoffer.
> 
> Any takers?

This looks like a rather interesting bugfix to me. :)  Though, I've 
unfortunately contracted some _nasty_ flu, so I'm still simply unable to 
work on pretty much anything in the next 5-6 days or so, at which point 
I hope to be operational again.

Thus, unless someone else can get it done faster, I should be able to 
start working on it in about a week or so.  Hopefully, that is.

> $ git shortlog --since=3.years -s -n -e --no-merges v2.43.0 
> builtin/mv.c
>     15	Shaoxuan Yuan <shaoxuan.yuan02@gmail.com>
>     10	Elijah Newren <newren@gmail.com>
>      5	Ævar Arnfjörð Bjarmason <avarab@gmail.com>
>      2	Junio C Hamano <gitster@pobox.com>
>      1	Andrzej Hunt <ajrhunt@google.com>
>      1	Calvin Wan <calvinwan@google.com>
>      1	Derrick Stolee <stolee@gmail.com>
>      1	Sebastian Thiel <sebastian.thiel@icloud.com>
>      1	Torsten Bögershausen <tboegi@web.de>