dirCreateDirPath

fn dirCreateDirPath(
    userdata: ?*anyopaque,
    dir: Dir,
    sub_path: []const u8,
    permissions: Dir.Permissions,
) Dir.CreateDirPathError!Dir.CreatePathStatus {
    const t: *Threaded = @ptrCast(@alignCast(userdata));

    var it = Dir.path.componentIterator(sub_path);
    var status: Dir.CreatePathStatus = .existed;
    var component = it.last() orelse return error.BadPathName;
    while (true) {
        if (dirCreateDir(t, dir, component.path, permissions)) |_| {
            status = .created;
        } else |err| switch (err) {
            error.PathAlreadyExists => {
                // It is important to return an error if it's not a directory
                // because otherwise a dangling symlink could cause an infinite
                // loop.
                const kind = try filePathKind(t, dir, component.path);
                if (kind != .directory) return error.NotDir;
            },
            error.FileNotFound => |e| {
                component = it.previous() orelse return e;
                continue;
            },
            else => |e| return e,
        }
        component = it.next() orelse return status;
    }
}