RFR JDK-8176379: java.util.Base64 mime encoder behaves incorrectly if initialized with a line length of size 1-3

[Paul Sandoz]

Base64
—

138 lineLength = lineLength >> 2 << 2;

I know the code was shuffled up but i find the following clearer in terms of bit manipulation:

  // Round down to nearest mulitple of 4
  lineLength &= ~0b11


TestBase64
—

Is there a test passing in a negative value for len?

Thanks,
Paul.


> On Jan 26, 2018, at 3:32 PM, Xueming Shen <xueming.shen at oracle.com> wrote:
> 
> Hi,
> 
> Please help review the change for JDK-8176379
> 
> issue: https://bugs.openjdk.java.net/browse/JDK-8176379
> webrev: http://cr.openjdk.java.net/~sherman/8176379/webrev
> 
> It appears the spec is somewhat misleading and/or incorrect in this corner
> case. And the implementation of the mime type encoder OutputStream does
> not expect a "length==0" mime encoder. The difference behavior of the
> non-stream-type encoder and stream-type encoder comes from
> 
> in non-stream-type case, we always have a " > 0" guard as
> 
>           if (linemax > 0 && slen > linemax / 4 * 3)
>                slen = linemax / 4 * 3
> 
> but in stream-type we don't.
> 
>        private void checkNewline() throws IOException {
>            if (linepos == linemax) {
>                out.write(newline);
>                linepos = 0;
>            }
>        }
> 
> The proposed change here is to clarify the spec and the implementation
> to use a non-mime type encoder (no line separator) when the rounded down
> mime line length is smaller than 4.
> 
> We probably need a CSR for this spec clarification, if the proposed change is
> approved.
> 
> Thanks,
> Sherman