sub callback_readdir
{
    my ($folder, $proc) = @_;

    if(opendir(DIR, $folder))
    {
        while(defined(my $file = readdir(DIR)))
        {
            next if $file =~ /^\.\.?$/;
            next if -f "$folder/$file";

            $proc->("$folder/$file");
        }

        closedir(DIR);
    }
}

...


callback_readdir($path, \&rmtree);