src/Stream.php
public function tell()
    {
        if (!is_resource($this->fp) || ($position = ftell($this->fp)) === false) {
            throw new \RuntimeException('Unable to get position of pointer in stream');
        }

        return $position;
    }
public function tell()
    {
        if (!is_resource($this->fp) || ($position = ftell($this->fp)) === false) {
            throw new \RuntimeException('Unable to get position of pointer in stream');
        }

        return $position;
    }
Returns the current position of the file read/write pointer

@return int Position of the file pointer
@throws \RuntimeException on error.