yii\web\Response::getHttpRange PHP Метод

    protected function getHttpRange($fileSize)
    {
        if (!isset($_SERVER['HTTP_RANGE']) || $_SERVER['HTTP_RANGE'] === '-') {
            return [0, $fileSize - 1];
        }
        if (!preg_match('/^bytes=(\\d*)-(\\d*)$/', $_SERVER['HTTP_RANGE'], $matches)) {
            return false;
        }
        if ($matches[1] === '') {
            $start = $fileSize - $matches[2];
            $end = $fileSize - 1;
        } elseif ($matches[2] !== '') {
            $start = $matches[1];
            $end = $matches[2];
            if ($end >= $fileSize) {
                $end = $fileSize - 1;
            }
        } else {
            $start = $matches[1];
            $end = $fileSize - 1;
        }
        if ($start < 0 || $start > $end) {
            return false;
        } else {
            return [$start, $end];
        }
    }