RFR: 8357425: (fs) SecureDirectoryStream setPermissions should use fchmodat [v4]

[Alan Bateman]

On Mon, 2 Jun 2025 16:16:07 GMT, Brian Burkhalter <bpb at openjdk.org> wrote:

>> Modify to use the `fchmodat(2)` system call to set permissions where possible to do so. This fixes the problem presented in the issue description.
>
> Brian Burkhalter has updated the pull request incrementally with one additional commit since the last revision:
> 
>   8357425: Use try-with-resources in test

Marked as reviewed by alanb (Reviewer).

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PR Review: https://git.openjdk.org/jdk/pull/25534#pullrequestreview-2893085503