[GSoC][PATCH v4 4/4] submodule: port submodule subcommand 'status' from shell to C

+ const char *const git_submodule_helper_usage[] = { + N_("git submodule status [--quiet] [--cached] [--recursive] [<path>]"), + NULL

the manpage over here says

  git submodule [--quiet] status [--cached] [--recursive] [--] [<path>...]

ie. multiple path arguments. Should this usage string be tweaked?

+static void print_status(struct status_cb *info, char state, const char *path, + const struct object_id *oid, const char *displaypath) +{

could do with a comment. What are the options for the `state` char?

+ if (state == ' ' || state == '+') { + struct argv_array get_rev_args = ARGV_ARRAY_INIT; + + argv_array_pushl(&get_rev_args, "get-rev-name", + path, oid_to_hex(oid), NULL); + get_rev_name(get_rev_args.argc, get_rev_args.argv, + info->prefix);

since you're not really subprocessing, can't you simply have a

  do_print_rev_name(char *path, char *sha) {
     ..
     printf("\n");
  }

and call that directly? Or call compute_rev_name directly. Then you don't have to do argv setup here.

Also, the name get_rev_name() is a little unfortunate, since it doesn't return a name, but rather prints it. Maybe the functions implementing helper commands could be named like:

  command_get_rev_name

or similar.