Re: [GSoC][PATCH 5/6] submodule: port submodule subcommand sync from shell to C

> The mechanism used for porting the submodule subcommand 'sync' is
> similar to that of 'foreach', where we split the function cmd_sync
> from shell into three functions in C, module_sync,
> for_each_submodule_list and sync_submodule.
>
> print_default_remote is introduced as a submodule--helper
> subcommand for getting the default remote as stdout.
>
> Mentored-by: Christian Couder <christian.couder@gmail.com>
> Mentored-by: Stefan Beller <sbeller@google.com>
> Signed-off-by: Prathamesh Chavan <pc44800@gmail.com>
> ---

>  builtin/submodule--helper.c | 180 ++++++++++++++++++++++++++++++++++++++++++++
>  git-submodule.sh            |  56 +-------------
>  2 files changed, 181 insertions(+), 55 deletions(-)
>
> diff --git a/builtin/submodule--helper.c b/builtin/submodule--helper.c
> index 78b21ab22..e10cac462 100644
> --- a/builtin/submodule--helper.c
> +++ b/builtin/submodule--helper.c
> @@ -43,6 +43,20 @@ static char *get_default_remote(void)
>         return ret;
>  }
>
> +static int print_default_remote(int argc, const char **argv, const char *prefix)
> +{
> +       const char *remote;
> +
> +       if (argc != 1)
> +               die(_("submodule--helper print-default-remote takes no arguments"));
> +
> +       remote = get_default_remote();
> +       if (remote)
> +               puts(remote);
> +
> +       return 0;
> +}
> +
>  static int starts_with_dot_slash(const char *str)
>  {
>         return str[0] == '.' && is_dir_sep(str[1]);
> @@ -311,6 +325,25 @@ static int print_name_rev(int argc, const char **argv, const char *prefix)
>         return 0;
>  }
>
> +static char *get_up_path(const char *path)
> +{
> +       int i = count_slashes(path);
> +       struct strbuf sb = STRBUF_INIT;
> +
> +       while (i--)
> +               strbuf_addstr(&sb, "../");
> +
> +       /*
> +        *Check if 'path' ends with slash or not
> +        *for having the same output for dir/sub_dir
> +        *and dir/sub_dir/
> +        */
> +       if (!is_dir_sep(path[i - 1]))
> +               strbuf_addstr(&sb, "../");
> +
> +       return strbuf_detach(&sb, NULL);
> +}
> +
>  struct module_list {
>         const struct cache_entry **entries;
>         int alloc, nr;
> @@ -736,6 +769,151 @@ static int module_name(int argc, const char **argv, const char *prefix)
>         return 0;
>  }
>
> +struct sync_cb {
> +       const char *prefix;
> +       unsigned int quiet: 1;
> +       unsigned int recursive: 1;
> +};
> +#define SYNC_CB_INIT { NULL, 0, 0 }
> +
> +static void sync_submodule(const struct cache_entry *list_item, void *cb_data)
> +{
> +       struct sync_cb *info = cb_data;
> +       const struct submodule *sub;
> +       char *sub_key, *remote_key;
> +       char *url, *sub_origin_url, *super_config_url, *displaypath;
> +       struct strbuf sb = STRBUF_INIT;
> +       struct child_process cp = CHILD_PROCESS_INIT;
> +
> +       if (!is_submodule_initialized(list_item->name))
> +               return;
> +
> +       sub = submodule_from_path(null_sha1, list_item->name);
> +
> +       if (!sub->url)