$fp = fopen($filename, 'c+');
if (flock($fp, LOCK_EX)) {
$buf = '';
while ($tmp = fread($fp, 1024)) {
$buf .= $tmp;
}
rewind($fp);
ftruncate($fp, 0);
fwrite($fp, $buf.$buf);
flock($fp, LOCK_UN)
}