Detect whether a file has a bom header - PHP

Detect whether a file has a bom header - PHP

//This file is used to quickly test whether the UTF8 encoded file has a BOM added and can be automatically removed
//By Bob Shen

$basedir="."; //Modify this The directory whose behavior needs to be detected, dot indicates the current directory
$auto=1; //Whether to automatically remove the discovered BOM information. 1 means yes, 0 means no.

//No need to change the following

if ($dh = opendir($basedir)) {
while (($file = readdir($dh)) !== false) {
if ($file!='.' && $file!='..' && !is_dir($basedir."/".$file)) echo "filename: $file ".checkBOM("$basedir/$file")." ";
}
closedir($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 ("BOM found, automatically removed.");
} else {
return ("BOM found .");
}
}
else return ("BOM Not Found.");
}

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