Re: [GSoC] [PATCH v2] submodule--helper: introduce add-config subcommand

[Kaartic Sivaraam <kaartic.sivaraam@gmail.com>]

Hi Atharva,

On 28/07/21 5:23 pm, Atharva Raykar wrote:
> Add a new "add-config" subcommand to `git submodule--helper` with the
> goal of converting part of the shell code in git-submodule.sh related to
> `git submodule add` into C code. This new subcommand sets the
> configuration variables of a newly added submodule, by registering the
> url in local git config, as well as the submodule name and path in the
> .gitmodules file. It also sets 'submodule.<name>.active' to "true" if
> the submodule path has not already been covered by any pathspec
> specified in 'submodule.active'.
> 
> This is meant to be a faithful conversion from shell to C, with only one
> minor change: A warning is emitted if no value is specified in
> 'submodule.active', ie, the config looks like: "[submodule] active\n",
> because it is an invalid configuration. It would be helpful to let the
> user know that the pathspec is unset, and the value of
> 'submodule.<name>.active' might be set to 'true' so that they can
> rectify their configuration and prevent future surprises (especially
> given that the latter variable has a higher priority than the former).
> 

v2 doesn't have the warning that this paragraph describes. So, this could
be dropped.

> [ snip ]
>
> A comment has been
> added to explain that only one value of 'submodule.active' is obtained
> to check if we need to call is_submodule_active() at all.
>

This could be me likely not understanding this properly. Anyways, where
is this comment in the code? I only see a comment about how 'is_submodule_active'
iterates over all values. I couldn't find any "one value" reference in it.
  
> Signed-off-by: Atharva Raykar <raykar.ath@gmail.com>
> Mentored-by: Christian Couder <christian.couder@gmail.com>
> Mentored-by: Shourya Shukla <periperidip@gmail.com>
> Based-on-patch-by: Shourya Shukla <periperidip@gmail.com>
> Based-on-patch-by: Prathamesh Chavan <pc44800@gmail.com>
> ---
> 
> Changes since v1:
> 
> * Remove the extra handling for the case where submodule.active is valueless, as
>    Junio pointed out that it is better dealt with in a cleanup patch.
> 
> * Do not discard error returns from 'config_submodule_in_gitmodules()', and also
>    ensure that any calls to it in 'configure_added_submodule()' die on failure,
>    like with the original shell porcelain.
> 
> * Style fixes.
> 
>   builtin/submodule--helper.c | 120 ++++++++++++++++++++++++++++++++++++
>   git-submodule.sh            |  28 +--------
>   2 files changed, 121 insertions(+), 27 deletions(-)
> 
> diff --git a/builtin/submodule--helper.c b/builtin/submodule--helper.c
> index 862053c9f2..60b47492cb 100644
> --- a/builtin/submodule--helper.c
> +++ b/builtin/submodule--helper.c
> @@ -2936,6 +2936,125 @@ static int add_clone(int argc, const char **argv, const char *prefix)
>   	return 0;
>   }
>   
> +static int config_submodule_in_gitmodules(const char *name, const char *var, const char *value)
> +{
> +	char *key;
> +	int ret;
> +
> +	if (!is_writing_gitmodules_ok())
> +		die(_("please make sure that the .gitmodules file is in the working tree"));
> +
> +	key = xstrfmt("submodule.%s.%s", name, var);
> +	ret = config_set_in_gitmodules_file_gently(key, value);
> +	free(key);
> +
> +	return ret;
> +}
> +
> +static void configure_added_submodule(struct add_data *add_data)
> +{
> +	char *key;
> +	char *val = NULL;
> +	struct child_process add_submod = CHILD_PROCESS_INIT;
> +	struct child_process add_gitmodules = CHILD_PROCESS_INIT;
> +
> +	key = xstrfmt("submodule.%s.url", add_data->sm_name);
> +	git_config_set_gently(key, add_data->realrepo);
> +	free(key);
> +
> +	add_submod.git_cmd = 1;
> +	strvec_pushl(&add_submod.args, "add",
> +		     "--no-warn-embedded-repo", NULL);
> +	if (add_data->force)
> +		strvec_push(&add_submod.args, "--force");
> +	strvec_pushl(&add_submod.args, "--", add_data->sm_path, NULL);
> +
> +	if (run_command(&add_submod))
> +		die(_("Failed to add submodule '%s'"), add_data->sm_path);
> +

> +	if (config_submodule_in_gitmodules(add_data->sm_name, "path", add_data->sm_path) ||
> +	    config_submodule_in_gitmodules(add_data->sm_name, "url", add_data->repo))
> +		die(_("Failed to register submodule '%s'"), add_data->sm_path);
> +
> +	if (add_data->branch)
> +		if (config_submodule_in_gitmodules(add_data->sm_name,
> +						   "branch", add_data->branch))
> +			die(_("Failed to register submodule '%s'"), add_data->sm_path);
> +
> +	add_gitmodules.git_cmd = 1;
> +	strvec_pushl(&add_gitmodules.args,
> +		     "add", "--force", "--", ".gitmodules", NULL);
> +
> +	if (run_command(&add_gitmodules))
> +		die(_("Failed to register submodule '%s'"), add_data->sm_path);
> +

We could restructure this portion like so ...

-- 8< --
         add_gitmodules.git_cmd = 1;
         strvec_pushl(&add_gitmodules.args,
                      "add", "--force", "--", ".gitmodules", NULL);
                                                                                                                                                                                              
         if (config_submodule_in_gitmodules(add_data->sm_name, "path", add_data->sm_path) ||
             config_submodule_in_gitmodules(add_data->sm_name, "url", add_data->repo) ||
             (add_data->branch && config_submodule_in_gitmodules(add_data->sm_name,
                                                                 "branch", add_data->branch)) ||
             run_command(&add_gitmodules))
                 die(_("Failed to register submodule '%s'"), add_data->sm_path);
-- >8 --

.. to avoid the redundant "Failed to register submodule ..." error message.
Whether the restructured version has poor readability or not is debatable, though.
                           
> +	/*
> +	 * NEEDSWORK: In a multi-working-tree world this needs to be
> +	 * set in the per-worktree config.
> +	 *

It might be a good idea to differentiate the NEEDSWORK comment from an informative
comment about the code snippet.

Also, you could add another NEEDSWORK/TODO comment regarding the change
to 'is_submodule_active' which you mention before[1].

[1]: https://public-inbox.org/git/a6de518a-d4a2-5a2b-28e2-ca8b62f2c85b@gmail.com/

> +	 * If submodule.active does not exist, or if the pathspec was unset,
> +	 * we will activate this module unconditionally.
> +	 *
> +	 * Otherwise, we ask is_submodule_active(), which iterates
> +	 * through all the values of 'submodule.active' to determine
> +	 * if this module is already active.
> +	 */
> +	if (git_config_get_string("submodule.active", &val) ||
> +	    !is_submodule_active(the_repository, add_data->sm_path)) {
> +		key = xstrfmt("submodule.%s.active", add_data->sm_name);
> +		git_config_set_gently(key, "true");
> +		free(key);
> +	}

It might be a good idea to expand this condition similar to the scripted version,
to retain the following comment which seems like a useful one to keep.

> [ snip ]
>
> -	if git config --get submodule.active >/dev/null
> -	then
> -		# If the submodule being adding isn't already covered by the
> -		# current configured pathspec, set the submodule's active flag
> -		if ! git submodule--helper is-active "$sm_path"
> -		then
> -			git config submodule."$sm_name".active "true"
> -		fi
> -	else
> -		git config submodule."$sm_name".active "true"
> -	fi

> +	git submodule--helper add-config ${force:+--force} ${branch:+--branch "$branch"} --url "$repo" --resolved-url "$realrepo" --path "$sm_path" --name "$sm_name"
>   }
>   
>   #
> 

-- 
Sivaraam