Contao\Controller::sendFileToBrowser PHP Method

    public static function sendFileToBrowser($strFile)
    {
        // Make sure there are no attempts to hack the file system
        if (preg_match('@^\\.+@i', $strFile) || preg_match('@\\.+/@i', $strFile) || preg_match('@(://)+@i', $strFile)) {
            throw new PageNotFoundException('Invalid file name');
        }
        // Limit downloads to the files directory
        if (!preg_match('@^' . preg_quote(\Config::get('uploadPath'), '@') . '@i', $strFile)) {
            throw new PageNotFoundException('Invalid path');
        }
        // Check whether the file exists
        if (!file_exists(TL_ROOT . '/' . $strFile)) {
            throw new PageNotFoundException('File not found');
        }
        $objFile = new \File($strFile);
        $arrAllowedTypes = \StringUtil::trimsplit(',', strtolower(\Config::get('allowedDownload')));
        // Check whether the file type is allowed to be downloaded
        if (!in_array($objFile->extension, $arrAllowedTypes)) {
            throw new AccessDeniedException(sprintf('File type "%s" is not allowed', $objFile->extension));
        }
        // HOOK: post download callback
        if (isset($GLOBALS['TL_HOOKS']['postDownload']) && is_array($GLOBALS['TL_HOOKS']['postDownload'])) {
            foreach ($GLOBALS['TL_HOOKS']['postDownload'] as $callback) {
                static::importStatic($callback[0])->{$callback[1]}($strFile);
            }
        }
        // Send the file (will stop the script execution)
        $objFile->sendToBrowser();
    }