503 lines
15 KiB
Rust
503 lines
15 KiB
Rust
use std::array;
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use bytes::{Buf, BufMut, BytesMut};
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use chrono::Duration;
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/// Classic C struct for utmp data for a single user session.
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///
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/// This struct is used in the rwhod protocol by being interpreted as raw bytes to be sent over UDP.
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#[derive(Debug, Clone)]
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#[repr(C)]
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pub struct Outmp {
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/// tty name
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pub out_line: [u8; Self::MAX_TTY_NAME_LEN],
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/// user id
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pub out_name: [u8; Self::MAX_USER_ID_LEN],
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/// time on
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pub out_time: i32,
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}
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impl Outmp {
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pub const MAX_TTY_NAME_LEN: usize = 8;
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pub const MAX_USER_ID_LEN: usize = 8;
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}
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/// Classic C struct for a single user session.
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///
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/// This struct is used in the rwhod protocol by being interpreted as raw bytes to be sent over UDP.
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#[derive(Debug, Clone)]
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#[repr(C)]
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pub struct Whoent {
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/// active tty info
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pub we_utmp: Outmp,
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/// tty idle time
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pub we_idle: i32,
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}
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impl Whoent {
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pub const SIZE: usize = std::mem::size_of::<Self>();
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fn zeroed() -> Self {
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Self {
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we_utmp: Outmp {
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out_line: [0u8; Outmp::MAX_TTY_NAME_LEN],
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out_name: [0u8; Outmp::MAX_USER_ID_LEN],
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out_time: 0,
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},
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we_idle: 0,
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}
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}
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fn is_zeroed(&self) -> bool {
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self.we_utmp.out_line.iter().all(|&b| b == 0)
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&& self.we_utmp.out_name.iter().all(|&b| b == 0)
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&& self.we_utmp.out_time == 0
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&& self.we_idle == 0
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}
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}
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/// Classic C struct for a rwhod status update.
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///
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/// This struct is used in the rwhod protocol by being interpreted as raw bytes to be sent over UDP.
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#[derive(Debug, Clone)]
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#[repr(C)]
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pub struct Whod {
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/// protocol version
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pub wd_vers: u8,
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/// packet type, see below
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pub wd_type: u8,
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pub wd_pad: [u8; 2],
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/// time stamp by sender
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pub wd_sendtime: i32,
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/// time stamp applied by receiver
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pub wd_recvtime: i32,
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/// host's name
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pub wd_hostname: [u8; Self::MAX_HOSTNAME_LEN],
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/// load average as in uptime
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pub wd_loadav: [i32; 3],
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/// time system booted
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pub wd_boottime: i32,
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pub wd_we: [Whoent; Self::MAX_WHOENTRIES],
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}
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impl Whod {
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pub const HEADER_SIZE: usize = 1 + 1 + 2 + 4 + 4 + Self::MAX_HOSTNAME_LEN + 4 * 3 + 4;
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pub const MAX_SIZE: usize = std::mem::size_of::<Self>();
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pub const MAX_HOSTNAME_LEN: usize = 32;
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pub const MAX_WHOENTRIES: usize = 1024 / std::mem::size_of::<Whoent>();
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pub const WHODVERSION: u8 = 1;
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// NOTE: there was probably meant to be more packet types, but only status is defined.
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pub const WHODTYPE_STATUS: u8 = 1;
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pub fn new(
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sendtime: i32,
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recvtime: i32,
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hostname: [u8; Self::MAX_HOSTNAME_LEN],
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loadav: [i32; 3],
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boottime: i32,
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whoentries: [Whoent; Self::MAX_WHOENTRIES],
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) -> Self {
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debug_assert!(
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whoentries
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.iter()
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.skip_while(|entry| !entry.is_zeroed())
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.all(|entry| entry.is_zeroed())
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);
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Self {
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wd_vers: Self::WHODVERSION,
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wd_type: Self::WHODTYPE_STATUS,
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wd_pad: [0u8; 2],
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wd_sendtime: sendtime,
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wd_recvtime: recvtime,
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wd_hostname: hostname,
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wd_loadav: loadav,
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wd_boottime: boottime,
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wd_we: whoentries,
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}
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}
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pub fn to_bytes(&self) -> [u8; Whod::MAX_SIZE] {
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let mut buf = BytesMut::with_capacity(Whod::MAX_SIZE);
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buf.put_u8(self.wd_vers);
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buf.put_u8(self.wd_type);
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buf.put_slice(&self.wd_pad);
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buf.put_i32(self.wd_sendtime);
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buf.put_i32(self.wd_recvtime);
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buf.put_slice(&self.wd_hostname);
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buf.put_i32(self.wd_loadav[0]);
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buf.put_i32(self.wd_loadav[1]);
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buf.put_i32(self.wd_loadav[2]);
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buf.put_i32(self.wd_boottime);
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for whoent in &self.wd_we {
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buf.put_slice(&whoent.we_utmp.out_line);
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buf.put_slice(&whoent.we_utmp.out_name);
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buf.put_i32(whoent.we_utmp.out_time);
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buf.put_i32(whoent.we_idle);
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}
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// SAFETY: this should never happen, Whod::MAX_SIZE is computed from the struct size
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buf
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.to_vec()
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.try_into()
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.expect("Buffer length mismatch, this should never happen")
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}
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pub fn from_bytes(input: &[u8]) -> anyhow::Result<Self> {
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if input.len() < Self::HEADER_SIZE {
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return Err(anyhow::anyhow!(
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"Not enough bytes to parse packet header: {} < {}",
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input.len(),
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Self::HEADER_SIZE
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));
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}
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if input.len() > Self::MAX_SIZE {
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return Err(anyhow::anyhow!(
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"Too many bytes to parse packet: {} > {}",
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input.len(),
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Self::MAX_SIZE
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));
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}
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if !(input.len() - Self::HEADER_SIZE).is_multiple_of(Whoent::SIZE) {
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return Err(anyhow::anyhow!(
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"Invalid packet length: {} (not aligned with struct sizes, should be {} + N * {})",
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input.len(),
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Self::HEADER_SIZE,
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Whoent::SIZE,
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));
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}
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let mut bytes = bytes::Bytes::copy_from_slice(input);
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let wd_vers = bytes.get_u8();
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debug_assert!(wd_vers == Self::WHODVERSION);
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let wd_type = bytes.get_u8();
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debug_assert!(wd_type == Self::WHODTYPE_STATUS);
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bytes.advance(2); // skip wd_pad
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let wd_sendtime = bytes.get_i32();
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let wd_recvtime = bytes.get_i32();
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let mut wd_hostname = [0u8; Self::MAX_HOSTNAME_LEN];
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bytes.copy_to_slice(&mut wd_hostname);
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let wd_loadav = [bytes.get_i32(), bytes.get_i32(), bytes.get_i32()];
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let wd_boottime = bytes.get_i32();
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debug_assert!(bytes.remaining() + Self::HEADER_SIZE == input.len());
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let mut wd_we = array::from_fn(|_| Whoent::zeroed());
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for (byte_chunk, whoent) in bytes.chunks_exact(Whoent::SIZE).zip(wd_we.iter_mut()) {
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let mut chunk_bytes = bytes::Bytes::copy_from_slice(byte_chunk);
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let mut out_line = [0u8; Outmp::MAX_TTY_NAME_LEN];
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chunk_bytes.copy_to_slice(&mut out_line);
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let mut out_name = [0u8; Outmp::MAX_USER_ID_LEN];
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chunk_bytes.copy_to_slice(&mut out_name);
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let out_time = chunk_bytes.get_i32();
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let we_utmp = Outmp {
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out_line,
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out_name,
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out_time,
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};
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let we_idle = chunk_bytes.get_i32();
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*whoent = Whoent { we_utmp, we_idle };
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}
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let result = Whod::new(
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wd_sendtime,
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wd_recvtime,
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wd_hostname,
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wd_loadav,
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wd_boottime,
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wd_we,
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);
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Ok(result)
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}
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}
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// ------------------------------------------------
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/// High-level representation of a rwhod status update.
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///
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/// This struct is intended for easier use in Rust code, with proper types and dynamic arrays.
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/// It can be converted to and from the low-level [`Whod`] struct used for network transmission.
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#[derive(Debug, Clone)]
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pub struct WhodStatusUpdate {
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// NOTE: there is only one defined packet type, so we just omit it here
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/// Timestamp by sender
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pub sendtime: chrono::DateTime<chrono::Utc>,
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/// Timestamp applied by receiver
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pub recvtime: Option<chrono::DateTime<chrono::Utc>>,
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/// Name of the host sending the status update (max 32 characters)
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pub hostname: String,
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/// load average over 5 minutes multiplied by 100
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pub load_average_5_min: i32,
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/// load average over 10 minutes multiplied by 100
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pub load_average_10_min: i32,
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/// load average over 15 minutes multiplied by 100
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pub load_average_15_min: i32,
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/// Which time the system was booted
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pub boot_time: chrono::DateTime<chrono::Utc>,
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/// List of users currently logged in to the host (max 42 entries)
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pub users: Vec<WhodUserEntry>,
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}
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impl WhodStatusUpdate {
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pub fn new(
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sendtime: chrono::DateTime<chrono::Utc>,
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recvtime: Option<chrono::DateTime<chrono::Utc>>,
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hostname: String,
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load_average_5_min: i32,
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load_average_10_min: i32,
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load_average_15_min: i32,
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boot_time: chrono::DateTime<chrono::Utc>,
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users: Vec<WhodUserEntry>,
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) -> Self {
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Self {
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sendtime,
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recvtime,
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hostname,
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load_average_5_min,
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load_average_10_min,
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load_average_15_min,
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boot_time,
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users,
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}
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}
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}
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/// High-level representation of a single user session in a rwhod status update.
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///
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/// This struct is intended for easier use in Rust code, with proper types.
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/// It can be converted to and from the low-level [`Whoent`] struct used for network transmission.
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#[derive(Debug, Clone)]
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pub struct WhodUserEntry {
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/// TTY name (max 8 characters)
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pub tty: String,
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/// User ID (max 8 characters)
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pub user_id: String,
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/// Time when the user logged in
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pub login_time: chrono::DateTime<chrono::Utc>,
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/// How long since the user last typed on the TTY
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pub idle_time: Duration,
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}
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impl WhodUserEntry {
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pub fn new(
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tty: String,
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user_id: String,
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login_time: chrono::DateTime<chrono::Utc>,
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idle_time: Duration,
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) -> Self {
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Self {
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tty,
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user_id,
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login_time,
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idle_time,
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}
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}
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}
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impl TryFrom<Whoent> for WhodUserEntry {
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type Error = String;
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fn try_from(value: Whoent) -> Result<Self, Self::Error> {
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let tty_end = value
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.we_utmp
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.out_line
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.iter()
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.position(|&c| c == 0)
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.unwrap_or(value.we_utmp.out_line.len());
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let tty = String::from_utf8(value.we_utmp.out_line[..tty_end].to_vec())
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.map_err(|e| format!("Invalid UTF-8 in TTY name: {}", e))?;
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let user_id_end = value
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.we_utmp
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.out_name
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.iter()
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.position(|&c| c == 0)
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.unwrap_or(value.we_utmp.out_name.len());
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let user_id = String::from_utf8(value.we_utmp.out_name[..user_id_end].to_vec())
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.map_err(|e| format!("Invalid UTF-8 in user ID: {}", e))?;
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let login_time = chrono::DateTime::from_timestamp_secs(value.we_utmp.out_time as i64)
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.ok_or(format!(
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"Invalid login time timestamp: {}",
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value.we_utmp.out_time
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))?;
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Ok(WhodUserEntry {
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tty,
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user_id,
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login_time,
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idle_time: Duration::seconds(value.we_idle as i64),
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})
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}
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}
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impl TryFrom<Whod> for WhodStatusUpdate {
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type Error = String;
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fn try_from(value: Whod) -> Result<Self, Self::Error> {
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if value.wd_vers != Whod::WHODVERSION {
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return Err(format!(
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"Unsupported whod protocol version: {}",
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value.wd_vers
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));
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}
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let sendtime = chrono::DateTime::from_timestamp_secs(value.wd_sendtime as i64).ok_or(
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format!("Invalid send time timestamp: {}", value.wd_sendtime),
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)?;
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let recvtime = if value.wd_recvtime == 0 {
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None
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} else {
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Some(
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chrono::DateTime::from_timestamp_secs(value.wd_recvtime as i64).ok_or(format!(
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"Invalid receive time timestamp: {}",
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value.wd_recvtime
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))?,
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)
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};
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let hostname_end = value
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.wd_hostname
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.iter()
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.position(|&c| c == 0)
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.unwrap_or(value.wd_hostname.len());
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let hostname = String::from_utf8(value.wd_hostname[..hostname_end].to_vec())
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.map_err(|e| format!("Invalid UTF-8 in hostname: {}", e))?;
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let boot_time = chrono::DateTime::from_timestamp_secs(value.wd_boottime as i64).ok_or(
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format!("Invalid boot time timestamp: {}", value.wd_boottime),
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)?;
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let users = value
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.wd_we
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.iter()
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.take_while(|whoent| !whoent.is_zeroed())
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.cloned()
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.map(WhodUserEntry::try_from)
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.collect::<Result<Vec<WhodUserEntry>, String>>()?;
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Ok(WhodStatusUpdate {
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sendtime,
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recvtime,
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hostname,
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load_average_5_min: value.wd_loadav[0],
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load_average_10_min: value.wd_loadav[1],
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load_average_15_min: value.wd_loadav[2],
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boot_time,
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users,
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})
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}
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}
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impl TryFrom<WhodUserEntry> for Whoent {
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type Error = String;
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fn try_from(value: WhodUserEntry) -> Result<Self, Self::Error> {
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let mut out_line = [0u8; Outmp::MAX_TTY_NAME_LEN];
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let tty_bytes = value.tty.as_bytes();
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out_line[..tty_bytes.len().min(Outmp::MAX_TTY_NAME_LEN)].copy_from_slice(tty_bytes);
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let mut out_name = [0u8; Outmp::MAX_USER_ID_LEN];
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let user_id_bytes = value.user_id.as_bytes();
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out_name[..user_id_bytes.len().min(Outmp::MAX_USER_ID_LEN)].copy_from_slice(user_id_bytes);
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let out_time = value
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.login_time
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.timestamp()
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.max(i32::MAX as i64)
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.min(i32::MIN as i64) as i32;
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let we_idle = value
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.idle_time
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.num_seconds()
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.max(i32::MAX as i64)
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.min(i32::MIN as i64) as i32;
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Ok(Whoent {
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we_utmp: Outmp {
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out_line,
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out_name,
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out_time,
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},
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we_idle,
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})
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}
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}
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impl TryFrom<WhodStatusUpdate> for Whod {
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type Error = String;
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fn try_from(value: WhodStatusUpdate) -> Result<Self, Self::Error> {
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let mut wd_hostname = [0u8; Whod::MAX_HOSTNAME_LEN];
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let hostname_bytes = value.hostname.as_bytes();
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wd_hostname[..hostname_bytes.len().min(Whod::MAX_HOSTNAME_LEN)]
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.copy_from_slice(hostname_bytes);
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let wd_sendtime = value
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.sendtime
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.timestamp()
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.max(i32::MAX as i64)
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.min(i32::MIN as i64) as i32;
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let wd_recvtime = value.recvtime.map_or(0, |dt| {
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dt.timestamp().max(i32::MAX as i64).min(i32::MIN as i64) as i32
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});
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let wd_boottime = value
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.boot_time
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.timestamp()
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.max(i32::MAX as i64)
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.min(i32::MIN as i64) as i32;
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let wd_we = value
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.users
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.into_iter()
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.map(Whoent::try_from)
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.chain(std::iter::repeat(Ok(Whoent::zeroed())))
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.take(Whod::MAX_WHOENTRIES)
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.collect::<Result<Vec<Whoent>, String>>()?
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.try_into()
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.expect("Length mismatch, this should never happen");
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Ok(Whod {
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wd_vers: Whod::WHODVERSION,
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wd_type: Whod::WHODTYPE_STATUS,
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wd_pad: [0u8; 2],
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wd_sendtime,
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wd_recvtime,
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wd_hostname,
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wd_loadav: [
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value.load_average_5_min,
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value.load_average_10_min,
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value.load_average_15_min,
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],
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wd_boottime,
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wd_we,
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})
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}
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}
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