批量清除BOM头

<?php  
//有些php文件由于不小心保存成了含bom头的格式而导致出现一系列的问题。以下是批量清除bom头的代码

if (isset ( $_GET ['dir'] )) { //config the basedir    
    $basedir = $_GET ['dir'];    
} else {    
    $basedir = '.';    
}    
$basedir="./weibo/";
$auto = 1;    

checkdir ( $basedir );    

function checkdir($basedir) {    
    if ($dh = opendir ( $basedir )) {    
        while ( ($file = readdir ( $dh )) !== false ) {    
            if ($file != '.' && $file != '..') {    
                if (! is_dir ( $basedir . "/" . $file )) { // 如果是文件    
                    echo "filename: $basedir/$file " . checkBOM ( "$basedir/$file" ) . " 
";    
                } else {    
                    $dirname = $basedir . "/" .$file; // 如果是目录    
                    checkdir ( $dirname ); // 递归    
                }    
            }    
        }    
        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 ( $charset [3] ) == 191) { // BOM 的前三个字符的ASCII 码分别为 239 187 191    
        if ($auto == 1) {    
            $rest = substr ( $contents, 3 );    
            rewrite ( $filename, $rest );    
            return ("");    
        } else {    
            return ("");    
        }    
    } else    
        return ("BOM Not Found.");    
}    

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