清除 bom php 代码

<?php 
set_time_limit(0);

function checkdir($basedir){
	if ($dh = opendir($basedir)){
		while (($file = readdir($dh)) !== false){
			if ($file != '.' && $file != '..'){
				if (!is_dir($basedir."/".$file)) {
					echo "filename: $basedir/$file ".checkBOM("$basedir/$file")." <br>";
				}else{
					$dirname = $basedir."/".$file;
					checkdir($dirname);
				}
			}
		}
		closedir($dh);
	}
}

function checkBOM ($filename){
	global $auto;
	$contents = file_get_contents($filename);
	$charset[1] = substr($contents, 0, 1);
	$charset[2] = substr($contents, 1, 1);
	$charset[3] = substr($contents, 2, 1);
	if(ord($charset[1]) == 239 && ord($charset[2]) == 187 && ord($charset[3]) == 191){
		if($auto == 1){
		   $rest = substr($contents, 3);
		   rewrite ($filename, $rest);
		   return ("<font color=red>BOM found, automatically removed.</font>");
		}else{
		   return ("<font color=red>BOM found.</font>");
		}
	}
	else return ("BOM Not Found.");
}

function rewrite($filename, $data){
	$filenum = fopen($filename, "w");
	flock($filenum, LOCK_EX);
	fwrite($filenum, $data);
	fclose($filenum);
}

if (isset($_GET['dir'])){
	$basedir=$_GET['dir'];
}else{
	$basedir = '.';
}
$auto = 1;
checkdir($basedir);

?>