<i18n dev> RFR: 8273111: Default timezone should return zone ID if /etc/localtime is valid but not canonicalization on linux

[Naoto Sato]

On Wed, 1 Sep 2021 06:45:26 GMT, Wu Yan <wuyan at openjdk.org> wrote:

> Hi,
> Please help me review the change to enhance getting  time zone ID from /etc/localtime on linux.
> 
> We use `realpath` instead of `readlink` to obtain the link name of /etc/localtime, because `readlink` can only read the value of a symbolic of link, not the canonicalized absolute pathname.
> 
> For example, the value of /etc/localtime is "../usr/share/zoneinfo//Asia/Shanghai", then the linkbuf obtained by `readlink` is "../usr/share/zoneinfo//Asia/Shanghai", and then the call of `getZoneName(linkbuf)` will get "/Asia/Shanghai", not "Asia/Shanghai", which consider as invalid in `ZoneInfoFile.getZoneInfo()`. Using `realpath`, you can get “/usr/share/zoneinfo/Asia/Shanghai“ directly from “/etc/localtime“.
> 
> Thanks,
> wuyan

The change looks reasonable. Please test your fix with macOS as well.

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PR: https://git.openjdk.java.net/jdk/pull/5327