$finfo = finfo_open(FILEINFO_MIME_TYPE);
$mime_type = finfo_file($finfo, $file);
finfo_close($finfo);
 
if ($mime_type == 'text/plain') {
    $pathinfos = pathinfo($file);
    $mime_type = 'text/'.$pathinfos['extension'];
}
 
 
header('Content-Type: '.$mime_type);

$mime_types = array(
            'txt' => 'text/plain',
            'htm' => 'text/html',
            'html' => 'text/html',
            'php' => 'text/html',
            'css' => 'text/css',
            'js' => 'application/javascript',
            'json' => 'application/json',
            'xml' => 'application/xml',
            'swf' => 'application/x-shockwave-flash',
            'flv' => 'video/x-flv',
 
            // images
            'png' => 'image/png',
            'jpe' => 'image/jpeg',
            'jpeg' => 'image/jpeg',
            'jpg' => 'image/jpeg',
            'gif' => 'image/gif',
            'bmp' => 'image/bmp',
            'ico' => 'image/vnd.microsoft.icon',
            'tiff' => 'image/tiff',
            'tif' => 'image/tiff',
            'svg' => 'image/svg+xml',
            'svgz' => 'image/svg+xml',
 
            // archives
            'zip' => 'application/zip',
            'rar' => 'application/x-rar-compressed',
            'exe' => 'application/x-msdownload',
            'msi' => 'application/x-msdownload',
            'cab' => 'application/vnd.ms-cab-compressed',
 
            // audio/video
            'mp3' => 'audio/mpeg',
            'qt' => 'video/quicktime',
            'mov' => 'video/quicktime',
 
            // adobe
            'pdf' => 'application/pdf',
            'psd' => 'image/vnd.adobe.photoshop',
            'ai' => 'application/postscript',
            'eps' => 'application/postscript',
            'ps' => 'application/postscript',
 
            // ms office
            'doc' => 'application/msword',
            'rtf' => 'application/rtf',
            'xls' => 'application/vnd.ms-excel',
            'ppt' => 'application/vnd.ms-powerpoint',
 
            // open office
            'odt' => 'application/vnd.oasis.opendocument.text',
            'ods' => 'application/vnd.oasis.opendocument.spreadsheet',
        );
 
        $infos = explode('.', $filename);
        $ext = strtolower(array_pop($infos));
        if (array_key_exists($ext, $mime_types)) {
            return $mime_types[$ext];
        }
        elseif (function_exists('finfo_open')) {
            $finfo = finfo_open(FILEINFO_MIME);
            $mimetype = finfo_file($finfo, $filename);
            finfo_close($finfo);
            return $mimetype;
        }
        else {
            return 'application/octet-stream';
        }