Use IOV_MAX and UIO_MAXIOV constants in limit vectored I/O

[Thomasdezeeuw]

Also updates the libc dependency to 0.2.77 (from 0.2.74) as the
constants were only recently added.

Related #68042, #75005

r? @Amanieu (also reviewed #75005)

[Thomasdezeeuw]

CI failed due to clock drift, could someone restart it?

[tesuji]

CI failed due to clock drift, could someone restart it?

You have to update Cargo.lock too: cargo update -p libc.

[Thomasdezeeuw]

CI failed due to clock drift, could someone restart it?

You have to update Cargo.lock too: cargo update -p libc.

@lzutao I'm ok with doing that, but how is that related to the clock drift?

Also I couldn't get it to only update the libc dependency, is alright to update other dependencies as well?

[tesuji]

I don't know what clock drift is, but the main problem why CI failed is that
CI enforces Cargo.lock integrity.

error: failed to write /checkout/Cargo.lock

Caused by:
  failed to open: /checkout/Cargo.lock

Running cargo update -p libc will update only libc crate.

[Thomasdezeeuw]

I don't know what clock drift is,

Clock drift is when the local clock's reported time differs from the "correct" time as reported by a known good clock.

Running cargo update -p libc will update only libc crate.

This failed initially, but I got it to work. Thanks.

[Thomasdezeeuw]

CI is complaining about an unneeded unsafe block in library/std/src/sys/unix/process/process_unix.rs, but I didn't touch that file.

[Amanieu]

It's because you updated the libc dependency. You should fix these errors.

[Thomasdezeeuw]

On macOS those function do require unsafe (that's why it didn't show up in my local testing). The definition on Linux: https://docs.rs/libc/0.2.77/libc/fn.WTERMSIG.html (no unsafe), vs https://docs.rs/libc/0.2.77/x86_64-apple-darwin/libc/fn.WTERMSIG.html (unsafe). I've opened rust-lang/libc#1888 for this.

@Amanieu would you be ok with putting #[allow(unused_unsafe)] around them for now? With a comment linking to rust-lang/libc#1888.

[Amanieu]

Put it under a linux-only #[cfg_attr] and add a comment linking to the issue.

[Thomasdezeeuw]

@Amanieu CI is now green.

[Amanieu]

@bors r+

[bors]

📌 Commit c394624 has been approved by Amanieu

[bors]

⌛ Testing commit c394624 with merge 85109af...

[bors]

☀️ Test successful - checks-actions, checks-azure
Approved by: Amanieu
Pushing 85109af to master...