[8u] [1/2] RFR backport of 8223490: Optimize search algorithm for determining default time zone

[David Alvarez]

Hi,

I would like to request a backport of JDK-8223490.

Bug: https://bugs.openjdk.java.net/browse/JDK-8223490
Original: https://hg.openjdk.java.net/jdk/jdk/rev/8ee083465318
Webrev: http://cr.openjdk.java.net/~alvdavi/webrevs/8223490/webrev.8u.00/

The patch is marked as 8u241 but not yet in openjdk8u242.

Patch did not apply cleanly, multiple modifications were required.

jkd8u missing JDK-8202794 [1] meant we still had the dirent64 *entry
around and references to readdir64_r. We also don't have JDK-7153347 [2]
which added multiple changes to the original findZoneInfoFile method.
Nor do we have JDK-8214077 [3] that changed statbuf to a stat64. It is
possible these are not the only ones.

This patch will be followed up by a backport of JDK-8231124 which is a
follow up.

I've run Tier1 and Tier2 tests, no regressions found. Additionally, I've
been able to test on an affected system, where ZoneId.systemDefault()
was returning Zulu before the patch, and UTC after.

Thanks,

David

--
[1] https://bugs.openjdk.java.net/browse/JDK-8202794
[2] http://hg.openjdk.java.net/jdk10/jdk10/jdk/rev/4887534fa39b
[3] https://bugs.openjdk.java.net/browse/JDK-8214077
[4] https://bugs.openjdk.java.net/browse/JDK-8231124