FreeBSD: Added xfile structure and file descriptor types

[antoncxx]

Description

Added binding for xfile structure from sys/file.h and descriptor types.

Sources

FreeBSD 15

• xfile
• descriptors

FreeBSD 14

• xfile
• descriptors

FreeBSD 13

• xfile
• descriptors

FreeBSD 12

• xfile
• descriptors

FreeBSD 11

• xfile
• descriptors

FreeBSD 10

• xfile
• descriptors

Checklist

• Relevant tests in libc-test/semver have been updated
• No placeholder or unstable values like *LAST or *MAX are
  included (see #3131)
• Tested locally (cd libc-test && cargo test --target mytarget);
  especially relevant for platforms that may not be checked in CI

@rustbot label +stable-nominated

[tgross35]

Cc @asomers for review

View changes since this review

[asomers]

What's the purpose of this PR? As far as I know, struct xfile is only exposed to the user via the KERN_FILE sysctl. That's fairly obscure. I would be ok if those definitions lived outside of the libc crate. It's up to Trevor if he thinks it's worthwhile to include.
And like Trevor said, you should drop everything related to FreeBSD 10 through12.

View changes since this review

[antoncxx]

What's the purpose of this PR? As far as I know, struct xfile is only exposed to the user via the KERN_FILE sysctl. That's fairly obscure. I would be ok if those definitions lived outside of the libc crate. It's up to Trevor if he thinks it's worthwhile to include. And like Trevor said, you should drop everything related to FreeBSD 10 through12.

View changes since this review

The motivation is what you described. I'm involved into development of a Rust library that performs KERN_FILE sysctl query, currently written in C, and I want to rewrite it in pure Rust. I could define the bindings locally, but since libc is already a dependency, I figured contributing them here might be useful to others as well.

[rustbot]

This PR was rebased onto a different main commit. Here's a range-diff highlighting what actually changed.

Rebasing is a normal part of keeping PRs up to date, so no action is needed—this note is just to help reviewers.