private void fillBuf() throws IOException {
        int result = in.read(buf, 0, buf.length);
        if (result == -1) {
            throw new EOFException();
        }
        pos = 0;
        end = result;
    }
Reads new input data into the buffer. Call only with pos == end or end == -1,
depending on the desired outcome if the function throws.
VideoSqlLite/src/main/java/com/yc/videosqllite/disk/StrictLineReader.java