main.rs

use nix::fcntl;
use nix::sys::select;
use std::io::Read;
use std::os::unix::io::AsRawFd;
use std::process;

fn main() {
    let mut path = std::env::current_exe().unwrap();
    path.set_file_name("teller");
    let mut proc = process::Command::new(&path)
        .stdout(process::Stdio::piped())
        .spawn()
        .unwrap();
    let mut stdout = proc.stdout.take().expect("Failed to take stdout.");
    let fd = stdout.as_raw_fd();
    let mut flags =
        fcntl::OFlag::from_bits(fcntl::fcntl(fd, fcntl::F_GETFL).expect("Failed reading flags"))
            .expect("Failed parsing flags");
    flags.insert(fcntl::OFlag::O_NONBLOCK);
    fcntl::fcntl(fd, fcntl::F_SETFL(flags)).expect("Failed to set flags.");
    let mut s = String::new();
    loop {
        let mut fds = select::FdSet::new();
        fds.insert(fd);
        dbg!(select::select(None, &mut fds, None, None, None));
        dbg!(stdout.read_to_string(&mut s));
    }
}