Re: [PATCH/WIP v2 03/19] am: implement skeletal builtin am

[Paul Tan <pyokagan@gmail.com>]

On Tue, Jun 16, 2015 at 1:54 AM, Junio C Hamano <gitster@pobox.com> wrote:
> Paul Tan <pyokagan@gmail.com> writes:
>
>>> The scripted Porcelain is spawned after applying patches 1-3 from
>>> here, when you do not have _GIT_USE_BUILTIN_AM exported.  Haven't
>>> RUN_SETUP code did its thing by that time?
>>
>> Ah right, the RUN_SETUP code would have chdir()-ed to the working
>> directory root, so git-am.sh will be unable to find the original
>> working directory. To aid it, we would have to chdir() back to the
>> original working directory, and unset GIT_DIR.
>
> I do not think that is a correct workaround, though.  GIT_DIR may
> have come from the end user, i.e.
>
>         $ GIT_WORK_TREE=somewhere GIT_DIR=somewhere.else git am ...

Ah, forgot about that ><

> As the RUN_SETUP|REQUIRE_WORK_TREE bit is merely a convenence in
> git.c, one workable way to keep these dual implementations is to do
> what built-in commands used to do before these were invented.
> Perhaps studying how cmd_diff(), which is run from git.c without
> either RUN_SETUP or NEED_WORK_TREE, and taking good bits from it
> would help.  I think the implementation roughly would look like
> this:
>
>         int cmd_am(int ac, const char **av, const char *prefix)
>         {
>                 /*
>                  * NEEDSWORK: once we retire the dual-mode
>                  * implementation, this preamble can be removed...
>                  */
>                 if (... want to do scripted ...) {
>                         ... spawn the scripted thing ...
>                 }
>                 prefix = setup_git_directory();
>                 setup_work_tree();
>                 /* ... up to this point */
>
>                 ... your real "git am in C" comes here ...
>         }
>

Ah OK. Just to be sure, I took a look at run_builtin() in git.c, and
indeed it only just does:

prefix = setup_git_directory();
trace_repo_setup(prefix);
setup_work_tree();

which is not bad at all. Thanks.

Regards,
Paul