Re: [GSoC][PATCH] submodule: port submodule subcommand 'add' from shell to C

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

Kaartic Sivaraam <kaartic.sivaraam@gmail.com> writes:

>> > 	else
>> > 		git ls-files -s "$sm_path" | sane_grep -v "^160000" > /dev/null 2>&1 &&
>> > 		die "$(eval_gettext "'\$sm_path' already exists in the index and is not a submodule")"
>> > 	fi
>> 
>> Hmph.  So,
>> 
>>  - if we are not being 'force'd, we see if there is anything in the
>>    index for the path and error out, whether it is a gitlink or not.
>> 
>
> Right.
>
>>  - if there is 'force' option, we see what the given path is in the
>>    index, and if it is already a gitlink, then die.  That sort of
>>    makes sense, as long as the remainder of the code deals with the
>>    path that is not a submodule in a sensible way.
>> 
>
> With `force, I think it's the opposite of what you describe. That is:
>
>     - if there is 'force' option, we see what the given path is in the
>       index, and if it is **not** already a gitlink, then die. 
>
> Note the `-v` passed to sane_grep.

Thanks.

Yeah, "-v ^160000" passes (i.e. detects an error) if the path exists
and it is anything but gitlink, so missing path is OK (no input to
grep, and grep won't see a gitlink), a blob is not OK (grep sees
something that is not a gitlink), and a gitlink is not OK.

If $sm_path is a directory with tracked contents, ls-files would
give multiple entries, and some of which may or may not be a
gitlink, but most of them would not be, so it is likely that grep
would find one entry that is not gitlink and error out.  Which is a
good thing to do.

>> > 	} else {
>> > 		int err;
>> > 		if (index_name_pos(&the_index, path, strlen(path)) >= 0 &&
>> > 		    !is_submodule_populated_gently(path, &err))
>> > 			die(_("'%s' already exists in the index and is not a "
>> > 			      "submodule"), path);
>> 
>> Likewise.  The above does much more than the original.
>> 
>> The original was checking if the found cache entry has 160000 mode
>> bit, so the second test would not be is_submodule_populated_gently()
>> but more like !S_ISGITLINK(ce->ce_mode)
>
> Yeah, the C version does need a more proper check in both cases.

Especially, the case where $sm_path is a directory with tracked
contents in it would need a careful examination.

Thanks.