8246282: [REDO] JDK-8245121 (bf) XBuffer.put(Xbuffer src) can give unexpected result when storage overlaps

[Brian Burkhalter]

Corrected subject line d’oh! s/1234567/8246282.


> On Jun 1, 2020, at 2:28 PM, Brian Burkhalter <brian.burkhalter at oracle.com> wrote:
> 
> In the patch for JDK-8245121 [1] I overlooked the case for XBuffer.putXBuffer(src) when src is neither direct nor heap [2]. In this case the base (hb) could be null and there is no memory address either. The patch is modified from that for JDK-8245121 to detect whether src is not direct and has a null base in which case the old loopy put is used. This case presently occurs only when src is a StringCharBuffer. The corrected patch is at [3]. Note that as StringCharBuffer is read-only, the reverse copy direction cannot occur, i.e., ‘this' is not direct and has a null base. Note that the patch [3] redoes the patch for [1] with this correction included.
> 
> I don’t know whether it might be better for the StringCharBuffer source case to get a handle to the internal String values array and use that directly. This would be a read-only access.
> 
> Regression tests are in progress.
> 
> Thanks,
> 
> Brian
> 
> [1] https://bugs.openjdk.java.net/browse/JDK-8245121
> [2] https://bugs.openjdk.java.net/browse/JDK-8246282
> [3] http://cr.openjdk.java.net/~bpb/8246282/webrev.00/