Re: [PATCHv4 3/3] submodule: implement `clone` as a builtin helper

> needed for converting `git submodule update` later on, which we want to
> add threading to.
>
> Signed-off-by: Stefan Beller <sbeller@google.com>
> ---
> diff --git a/builtin/submodule--helper.c b/builtin/submodule--helper.c
> index f5e408a..63f535a 100644
> --- a/builtin/submodule--helper.c
> +++ b/builtin/submodule--helper.c
> +static int module_clone(int argc, const char **argv, const char *prefix)
> +{
> +       const char *path = NULL, *name = NULL, *url = NULL;
> +       const char *reference = NULL, *depth = NULL;
> +       const char *alternative_path = NULL, *p;
> +       int quiet = 0;
> +       FILE *submodule_dot_git;
> +       char *sm_gitdir;
> +       struct strbuf rel_path = STRBUF_INIT;
> +       struct strbuf sb = STRBUF_INIT;
> +
> +       struct option module_clone_options[] = {
> +               OPT_STRING(0, "prefix", &alternative_path,
> +                          N_("path"),
> +                          N_("alternative anchor for relative paths")),
> +               OPT_STRING(0, "path", &path,
> +                          N_("path"),
> +                          N_("where the new submodule will be cloned to")),
> +               OPT_STRING(0, "name", &name,
> +                          N_("string"),
> +                          N_("name of the new submodule")),
> +               OPT_STRING(0, "url", &url,
> +                          N_("string"),
> +                          N_("url where to clone the submodule from")),
> +               OPT_STRING(0, "reference", &reference,
> +                          N_("string"),
> +                          N_("reference repository")),
> +               OPT_STRING(0, "depth", &depth,
> +                          N_("string"),
> +                          N_("depth for shallow clones")),
> +               OPT__QUIET(&quiet, "Suppress output for cloning a submodule"),
> +               OPT_END()
> +       };
> +
> +       const char * const git_submodule_helper_usage[] = {

> +               N_("git submodule--helper clone [--prefix=<path>] [--quiet] "
> +                  "[--reference <repository>] [--name <name>] [--url <url>]"
> +                  "[--depth <depth>] [--] [<path>...]"),
> +               NULL
> +       };
> +
> +       argc = parse_options(argc, argv, prefix, module_clone_options,
> +                            git_submodule_helper_usage, 0);
> +
> +       strbuf_addf(&sb, "%s/modules/%s", get_git_dir(), name);
> +       sm_gitdir = strbuf_detach(&sb, NULL);
> +
> +       if (!file_exists(sm_gitdir)) {
> +               if (safe_create_leading_directories_const(sm_gitdir) < 0)
> +                       die(_("could not create directory '%s'"), sm_gitdir);
> +               if (clone_submodule(path, sm_gitdir, url, depth, reference, quiet))
> +                       die(N_("clone of '%s' into submodule path '%s' failed"),
> +                           url, path);

> +       } else {
> +               if (safe_create_leading_directories_const(path) < 0)
> +                       die(_("could not create directory '%s'"), path);
> +               if (unlink(sm_gitdir) < 0)
> +                       die_errno(_("failed to delete '%s'"), sm_gitdir);
> +       }
> +
> +       /* Write a .git file in the submodule to redirect to the superproject. */
> +       if (alternative_path && *alternative_path)) {
> +               p = relative_path(path, alternative_path, &sb);
> +               strbuf_reset(&sb);
> +       } else
> +               p = path;
> +
> +       if (safe_create_leading_directories_const(p) < 0)
> +               die(_("could not create directory '%s'"), p);
> +
> +       strbuf_addf(&sb, "%s/.git", p);
> +
> +       if (safe_create_leading_directories_const(sb.buf) < 0)
> +               die(_("could not create leading directories of '%s'"), sb.buf);
> +       submodule_dot_git = fopen(sb.buf, "w");
> +       if (!submodule_dot_git)
> +               die (_("cannot open file '%s': %s"), sb.buf, strerror(errno));

> +       fprintf(submodule_dot_git, "gitdir: %s\n",
> +               relative_path(sm_gitdir, path, &rel_path));
> +       if (fclose(submodule_dot_git))
> +               die(_("could not close file %s"), sb.buf);
> +       strbuf_reset(&sb);
> +
> +       /* Redirect the worktree of the submodule in the superproject's config */
> +       if (strbuf_getcwd(&sb))
> +               die_errno(_("unable to get current working directory"));
> +
> +       if (!is_absolute_path(sm_gitdir)) {
> +               if (strbuf_getcwd(&sb))
> +                       die_errno(_("unable to get current working directory"));

> +               strbuf_addf(&sb, "/%s", sm_gitdir);
> +               free(sm_gitdir);
> +               sm_gitdir = strbuf_detach(&sb, NULL);
> +       }
> +
> +
> +       strbuf_addf(&sb, "/%s", path);
> +
> +       p = git_pathdup_submodule(path, "config");
> +       if (!p)
> +               die(_("could not get submodule directory for '%s'"), path);
> +       git_config_set_in_file(p, "core.worktree",
> +                              relative_path(sb.buf, sm_gitdir, &rel_path));
> +       strbuf_release(&sb);

> +       free(sm_gitdir);
> +       return 0;
> +}
>
>  struct cmd_struct {
>         const char *cmd;
> @@ -132,6 +271,7 @@ struct cmd_struct {
>  static struct cmd_struct commands[] = {
>         {"list", module_list},
>         {"name", module_name},
> +       {"clone", module_clone},
>  };