Given the fact that a directory handle is a typeglob (approximately) and recursion is always with us, I find the best way to do readdirs is "all at once", this reduces the chance that I will have two directory handles with the same name interfere with each other.

{
  my(@files,$file);
  local(*DIR);

  opendir(DIR,$dir_name);
  @files = readdir(DIR);
  closedir(DIR);

  foreach $file (@files)
    {
      next if(/^\.\.?/);
      ...
    }
}
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If you adopt this strategy then your question becomes "how do I find out if this item is last one on the list", and therefore very easy to answer.