RFR: 8316304: (fs) Add support for BasicFileAttributes.creationTime() for Linux [v10]

[Alan Bateman]

On Wed, 4 Oct 2023 19:15:01 GMT, Severin Gehwolf <sgehwolf at openjdk.org> wrote:

>> Please review this nio change which adds `BasicFileAttributes.creationTime()` support for Linux by means of the `statx` Linux specific system call. The patch does a dynamic lookup of the function and if it is available, uses it to set the support birth time capability in `UnixNativeDispatcher`. When `statx` is not available, it won't use it and fall back to the old behaviour on such systems. It should, however, compile fine on Linux systems not supporting the `statx` system call.
>> 
>> Testing:
>> - [x] GHA (MacOS X failure seems unrelated)
>> - [x] `java.nio` tests.
>> - [x] Manual builds and tests on older glibc versions (2.17 => fallback, 2.28+ => works). Compiles fine and falls back to the not supported case as it was before this patch.
>> 
>> Thoughts?
>
> Severin Gehwolf has updated the pull request incrementally with one additional commit since the last revision:
> 
>   Add missing returns when statx is available

test/jdk/java/nio/file/attribute/BasicFileAttributeView/CreationTime.java line 96:

> 94:             System.out.println("[Linux] Debug: supportsCreationTimeRead == " + supportsCreationTimeRead);
> 95:             // Creation time updates are not supported on Linux
> 96:             supportsCreationTimeWrite = false;

It might be simpler to use `Linker.nativeLinker().defaultLookup().find("statx").isPresent()` as that would avoid adding CreationTimeHelper. JEP 454 is proposed to target 22 so the test won't need @enablePreview.

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PR Review Comment: https://git.openjdk.org/jdk/pull/15792#discussion_r1349518168