批量清除BOM头

##把该文件放在需求去除BOM头的目录下跑一下却可。
<?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 )) { // 如果是文件
                    echo "filename: $basedir/$file " . checkBOM ( "$basedir/$file" ) . " <br>";
                } 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, $rest );
            return ("<font color=red>BOM found, automatically removed.</font>");
        } else {
            return ("<font color=red>BOM found.</font>");
        }
    } else
        return ("BOM Not Found.");
}
function rewrite($filename, $data) {
    $filenum = fopen ( $filename, "w" );
    flock ( $filenum, LOCK_EX );
    fwrite ( $filenum, $data );
    fclose ( $filenum );
}
?>