Re: [PATCH v2 2/4] git-p4: create new method gitRunHook

[Junio C Hamano <gitster@pobox.com>]

Ben Keene <seraphire@gmail.com> writes:

> On 2/5/2020 4:42 PM, Junio C Hamano wrote:
>> Ben Keene <seraphire@gmail.com> writes:
>>
>>>>> +        hooks_path = os.path.join(os.environ.get("GIT_DIR", ".git"), "hooks")
>>>> This assumes that the process when his function is called (by the
>>>> way, even though the title of the patch uses the word "method", this
>>>> is not a method but a function, no?), it is always at the top level
>>>> of the working tree.  Is that a good assumption?  I don't know the
>>>> code well, so "yes it is good because a very early thing we do is to
>>>> go up to the top" is a good answer.
>>> ...
> As best as I understand the mechanics, and I haven't examined the
> source code of git, this is just experimental,...

As I already said that I do not know the code well, it is useless
for you to also speculate.  One of us must read the code before
speaking further ;-)

I just scanned "def main()", and it seems that it always goes to the
top-level of the working tree by doing chdir(cdup), where cdup is
learned from "git rev-parse --show-cdup", i.e. "tell me how to chdir
up to the top-level of the working tree".

I am assuming that nobody runs "git p4" in a bare repository, so
under that assumption, I think it would be safe to say that we can
assume we are always at the top.  Also, GIT_DIR is exported from
there, so it probably is a good idea to make sure that the run-hook
helper just uses os.environ.get("GIT_DIR") and barfs if the environ
is not set (i.e. there is something funny going on) without
pretending that it is prepared to deal with such a case, which is
what the "[, default]" parameter to .get method is doing.

I.e.

	hooks_path = os.path.join(os.environ["GIT_DIR"], "hooks")
    
> Does this prompt the need to search the hierarchy if we don't find
> the directory?

No, we just saw that it is done early in "def main()".  It is done
by "rev-parse --git-dir" and "rev-parse --show-cdup".