PHP自动去掉BOM

if (isset($_GET['dir'])){ //设置文件目录  

$basedir=$_GET['dir'];  

}else{  

$basedir = '.';  

}  

$auto = 1;  

checkdir($basedir);  

function checkdir($basedir){  

if ($dh = opendir($basedir)) {  

  while (($file = readdir($dh)) !== false) {  

   if ($file != '.' && $file != '..'){  

    if (!is_dir($basedir."/".$file)) {  

     echo "<br>filename: $basedir/$file ".checkBOM("$basedir/$file");  

    }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);  

}