socket: change accept to return an OwnedFd

[cgzones]

accept(2) returns on success a new file descriptor that is not coupled with the listened socket. Thus it is safe to wrap it into an OwnedFd, which will close the socket on cleanup.

What does this PR do

Checklist:

• I have read CONTRIBUTING.md
• I have written necessary tests and rustdoc comments
• A change log has been added if this PR modifies nix's API

[SteveLauC]

LGTM, thanks for the patch!

I think we could take this a step further and make the sockfd argument I/O-safe as well:

fn accept<Fd: AsFd>(sockfd: Fd) -> Result<OwnedFd>

Are you interested in doing it in this PR

[SteveLauC]

CI failures are unrelated and fixed, you can rebase your branch.

[Copilot]

Pull request overview

This PR updates nix::sys::socket::accept to return an owning file-descriptor type (OwnedFd) rather than a RawFd, aligning the API with Rust I/O-safety patterns and avoiding call-site unsafe wrappers.

Changes:

• Change sys::socket::accept to return Result<OwnedFd> and wrap the returned fd in OwnedFd.
• Update socket-related tests to use the returned OwnedFd directly (removing BorrowedFd::borrow_raw workarounds).
• Add a changelog entry documenting the API change.

Reviewed changes

Copilot reviewed 4 out of 4 changed files in this pull request and generated 2 comments.

File	Description
src/sys/socket/mod.rs	Changes accept to return OwnedFd and wraps the returned fd.
test/sys/test_socket.rs	Removes raw-borrow workarounds and uses &OwnedFd with read/fcntl.
test/sys/test_sockopt.rs	Adjusts imports and removes an unnecessary manual OwnedFd::from_raw_fd wrapping after accept.
changelog/2780.changed.md	Documents the public API change for accept.

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[cgzones]

changed accept4 as well

[Copilot]

Pull request overview

Copilot reviewed 4 out of 4 changed files in this pull request and generated 7 comments.

[SteveLauC]

Thanks!