Function checked_cmsg_space

crates/stdlib/src/socket.rs:3472–3483

(len: usize)

    #[cfg(all(unix, not(target_os = "redox")))]
    fn checked_cmsg_space(len: usize) -> Option<usize> {
        // SAFETY: CMSG_SPACE is always safe
        let cmsg_space = |length| unsafe { libc::CMSG_SPACE(length) };
        if len as u64 > (i32::MAX as u64 - cmsg_space(1) as u64) {
            return None;
        }
        let res = cmsg_space(len as _) as usize;
        if res > i32::MAX as usize || res < len {
            return None;
        }
        Some(res)
    }

    #[cfg(all(unix, not(target_os = "redox")))]
    #[pyfunction(name = "CMSG_LEN")]