1234567: [REDO] JDK-8245121 (bf) XBuffer.put(Xbuffer src) can give unexpected result when storage overlaps

[Brian Burkhalter]

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/