RFR: 8375294: (fs) Files.copy can fail with EOPNOTSUPP when copy_file_range not supported

[Jaikiran Pai]

On Wed, 14 Jan 2026 18:26:52 GMT, Brian Burkhalter <bpb at openjdk.org> wrote:

> Handle `errno` value `EOPNOTSUPP` for `copy_file_range` system call on Linux.

Hello Brian, the change looks good to me. Interestingly `man copy_file_range` doesn't make a mention of this `errno`. Looking at `man errno` it says:


ENOSYS          Function not implemented (POSIX.1-2001).
...
ENOTSUP         Operation not supported (POSIX.1-2001).
...
EOPNOTSUPP      Operation not supported on socket (POSIX.1-2001).
                (ENOTSUP and EOPNOTSUPP have the same value on Linux, but according to POSIX.1 these error values should be distinct.)


Given this, do you think we should also include `ENOTSUP` in this change?

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Marked as reviewed by jpai (Reviewer).

PR Review: https://git.openjdk.org/jdk/pull/29234#pullrequestreview-3664172712