RFR: 8316304: (fs) Add support for BasicFileAttributes.creationTime() for Linux [v8]

[Brian Burkhalter]

On Tue, 3 Oct 2023 17:41:24 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 with a new target base due to a merge or a rebase. The incremental webrev excludes the unrelated changes brought in by the merge/rebase. The pull request contains 12 additional commits since the last revision:
> 
>  - Link libCreationTimeHelper with -ldl
>  - Merge branch 'master' into JDK-8316304-statx-create-time-new
>  - Cleanup UnixNativeDispatcher.c
>  - Refactor test so as to not use reflection
>  - Fix indents
>  - Check correct fieldID
>  - Add copyright
>  - Add support for nano seconds for btime on Linux
>  - Fix style
>  - Wrap copy_statx_attributes with ifdef __linux__
>  - ... and 2 more: https://git.openjdk.org/jdk/compare/65113b79...83347ec1

test/jdk/java/nio/file/attribute/BasicFileAttributeView/libCreationTimeHelper.c line 33:

> 31: {
> 32: #if defined(__linux__)
> 33:     void* statx_func = dlsym(RTLD_DEFAULT, "statx");

For commit 04226fd470bc9a238e83606cb7f62ebd64d44421, which is the penultimate commit, I am seeing the build error:


open/test/jdk/java/nio/file/attribute/BasicFileAttributeView/libCreationTimeHelper.c:33: error: undefined reference to 'dlsym'```

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PR Review Comment: https://git.openjdk.org/jdk/pull/15792#discussion_r1344525162