sub dir_size
{
    my $dir = shift;
    local *DIR;
    my $size = 0;
    my $file;

    opendir(DIR, $dir) or die "Failed to open $dir: $!\n";

    while ($file = readdir(DIR))
    {
        # Skip . and ..
        if ($file !~ /^\.\.?$/)
        {
            if (-d "$dir/$file")
            {
                $size += dir_size("$dir/$file");
            }
            else
            {
                $size += -s "$dir/$file";
            }
        }
    }


    closedir(DIR);

    return $size;
}

my $size = dir_size("/foo/bar");