Re: [PATCH] remote-hg: fix path when cloning with tilde expansion

[Felipe Contreras <felipe.contreras@gmail.com>]

On Sat, Aug 10, 2013 at 12:18 AM, Junio C Hamano <gitster@pobox.com> wrote:
> Felipe Contreras <felipe.contreras@gmail.com> writes:
>
>>> Hmph, do you mean the third example of this?
>>>
>>>         $ python
>>>         >>> import os
>>>         >>> os.path.expanduser("~/repo")
>>>         '/home/junio/repo'
>>>         >>> os.path.expanduser("~junio/repo")
>>>         '/home/junio/repo'
>>>         >>> os.path.expanduser("~felipe/repo")
>>>         '~felipe/repo'
>>>
>>> which will give "~felipe/repo" that is _not_ an absolute repository
>>> because no such user exists on this box?
>>>
>>> It is true that in that case fix_path() will not return early and
>>> will throw a bogus path at "git config", but if the "~whom" does not
>>> resolve to an existing home directory of a user, I am not sure what
>>> we can do better than what Antoine's patch does.
>>
>> I was thinking something like this:
>>
>> if url.scheme != 'file' or os.path.isabs(url.path) or url.path[0] == '~':
>>   return
>
> That did cross my mind.
>
> I know ~/ and ~who/ are expanded on UNIXy systems, and I read in
> Python documentation that Python on Windows treats ~/ and ~who/ the
> same way as on UNIXy systems, so the "begins with ~" test would work
> on both systems.  But it is probably a better design to outsource
> that knowledge to os.path.expanduser(), with the emphasis on "os."
> part of that function.  That way, we do not even have to care about
> such potential platform specifics, which is a big plus.  The only
> possible difference that approach makes is the above example of
> naming a non-existent ~user, but that will not work anyway, so...

We would be doing better than os.path.expanduser(), because if
Mercurial somehow decided to treat ~ differently, our code would still
work just fine. If we do os.path.expanduser(), then we are not
outsourcing anything, we are taking ownership and fixing the path by
ourselves and dealing with all the consequences.

If I clone ~/git, and then change my username, and move my home
directory, doing a 'git fetch' in ~/git wouldn't work anymore, because
we have expanded the path and fixed it to my old home, if instead we
simply return without fixing, it would still work just fine.

-- 
Felipe Contreras