[OpenJDK 2D-Dev] request for review: JDK-8028722: XRender: Drawing strings with exactly 254 glyphs causes hangs

[Clemens Eisserer]

Hi,

Please review my fix for JDK-8028722: "XRender: Drawing strings with
exactly 254 glyphs causes hangs" available at
http://cr.openjdk.java.net/~ceisserer/8028722/webrev.00/
A test is available at:
http://cr.openjdk.java.net/~ceisserer/8028722/XRenderElt254TextTest.java

Problem description:
When drawing strings with a length that is a multiple of 254
characters, the xrender pipeline hangs.
This is caused by a bug in libXrender/XRenderCompositeText32 which
calculates a wrong request length in this case and passes garbage
bytes to the xserver.

Fix description:
As a workarround, this fix forces a new elt to be used after 253
characters, doing the split exactly two characters before libXrender
would do it internally anyway.
A patch for libXrender is awaiting review currently.

Thank you in advance, Clemens