去除UTF8 BOM【转】

utf8的编码有no bom & bom 区分。

<?php   

if (isset($_GET['dir'])){ //config the basedir   
    $basedir=$_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 "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);   
}   

?>