procdog_agent/
lib.rs

1use std::{
2    env,
3    io::{PipeWriter, Write},
4    os::fd::{FromRawFd, RawFd},
5};
6
7#[derive(Debug, thiserror::Error)]
8pub enum Error {
9    #[error("Not running under procdog supervisor")]
10    Unsupervised,
11    #[error("procdog file descriptor number invalid")]
12    FdInvalid,
13    #[error("I/O error on procdog file handle ({0})")]
14    IoError(nix::Error),
15}
16
17pub struct ProcdogAgent {
18    writer: Option<PipeWriter>,
19}
20
21pub fn init(allow_unsupervised: bool) -> Result<ProcdogAgent, Error> {
22    if let Ok(s_fd) = env::var("PROCDOG_FD") {
23        let fd = RawFd::from_str_radix(&s_fd, 10).map_err(|_| Error::FdInvalid)?;
24        let writer = unsafe { PipeWriter::from_raw_fd(fd) };
25        nix::fcntl::fcntl(
26            &writer,
27            nix::fcntl::FcntlArg::F_SETFL(nix::fcntl::OFlag::O_NONBLOCK),
28        )
29        .map_err(|errno| Error::IoError(errno))?;
30        Ok(ProcdogAgent {
31            writer: Some(writer),
32        })
33    } else if allow_unsupervised {
34        Ok(ProcdogAgent { writer: None })
35    } else {
36        Err(Error::Unsupervised)
37    }
38}
39
40impl ProcdogAgent {
41    pub fn heartbeat(&mut self) {
42        if let Some(writer) = self.writer.as_mut() {
43            let buf = [b'H'];
44            writer
45                .write(&buf)
46                .expect("Error writing to procdog supervisor");
47        }
48    }
49}
procdog_agent/lib.rs

procdog_agent/
lib.rs
