读取文件头判断文件类型的php代码

$filename = "D:/296.mid";
$file = fopen($filename, "rb");
$bin = fread($file, 2); //只读2字节
fclose($file);
$strInfo = @unpack("C2chars", $bin);
$typeCode = intval($strInfo['chars1'].$strInfo['chars2']);
$fileType = '';
switch ($typeCode)
{
case 7790:
$fileType = 'exe';
break;
case 7784:
$fileType = 'midi';
break;
case 8297:
$fileType = 'rar';
break;
case 255216:
$fileType = 'jpg';
break;
case 7173:
$fileType = 'gif';
break;
case 6677:
$fileType = 'bmp';
break;
case 13780:
$fileType = 'png';
break;
default:
echo 'unknown';
}
echo 'this is a(an) '.$fileType.' file:'.$typeCode;
?>

linux下php还有个函数可以判断文件类型

echo mime_content_type('php.gif') . "\n";
echo mime_content_type('test.php');
?>