daemon 0.0.8

Library for creating simple Linux demons and Windows services.
Documentation 
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extern crate libc;

use super::daemon::*;
use std::io::{Error, ErrorKind};
use std::sync::mpsc::channel;
use std::sync::mpsc::Receiver;
use std::sync::mpsc::Sender;

declare_singleton!(
    singleton,
    DaemonHolder,
    DaemonHolder {
        holder: 0 as *mut DaemonStatic
    }
);

struct DaemonHolder {
    holder: *mut DaemonStatic,
}

struct DaemonStatic {
    holder: Box<DaemonFunc>,
}

trait DaemonFunc {
    fn exec(&mut self) -> Result<(), Error>;
    fn send(&mut self, state: State) -> Result<(), Error>;
    fn take_tx(&mut self) -> Option<Sender<State>>;
}

struct DaemonFuncHolder<F: FnOnce(Receiver<State>)> {
    tx: Option<Sender<State>>,
    func: Option<(F, Receiver<State>)>,
}

impl<F: FnOnce(Receiver<State>)> DaemonFunc for DaemonFuncHolder<F> {
    fn exec(&mut self) -> Result<(), Error> {
        match self.func.take() {
            Some((func, rx)) => {
                func(rx);
                Ok(())
            }
            None => Err(Error::new(
                ErrorKind::Other,
                "INTERNAL ERROR: Can't unwrap daemon function",
            )),
        }
    }

    fn send(&mut self, state: State) -> Result<(), Error> {
        match self.tx {
            Some(ref tx) => match tx.send(state) {
                Ok(_) => Ok(()),
                Err(e) => Err(Error::new(ErrorKind::Other, e)),
            },
            None => Err(Error::new(ErrorKind::Other, "Service is already exited")),
        }
    }

    fn take_tx(&mut self) -> Option<Sender<State>> {
        self.tx.take()
    }
}

fn daemon_wrapper<R, F: FnOnce(&mut DaemonHolder) -> R>(func: F) -> R {
    let singleton = singleton();
    let result = match singleton.lock() {
        Ok(ref mut daemon) => func(daemon),
        Err(e) => {
            panic!("Mutex error: {:?}", e);
        }
    };
    result
}

impl DaemonRunner for Daemon {
    fn run<F: 'static + FnOnce(Receiver<State>)>(&self, func: F) -> Result<(), Error> {
        let (tx, rx) = channel();
        tx.send(State::Start).unwrap();
        let mut daemon = DaemonStatic {
            holder: Box::new(DaemonFuncHolder {
                tx: Some(tx),
                func: Some((func, rx)),
            }),
        };
        try!(guard_compare_and_swap(daemon_null(), &mut daemon));
        let result = daemon_console(&mut daemon);
        try!(guard_compare_and_swap(&mut daemon, daemon_null()));
        result
    }
}

fn guard_compare_and_swap(
    old_value: *mut DaemonStatic,
    new_value: *mut DaemonStatic,
) -> Result<(), Error> {
    daemon_wrapper(|daemon_static: &mut DaemonHolder| -> Result<(), Error> {
        if daemon_static.holder != old_value {
            return Err(Error::new(
                ErrorKind::Other,
                "This function is not reentrant.",
            ));
        }
        daemon_static.holder = new_value;
        Ok(())
    })
}

fn daemon_console(daemon: &mut DaemonStatic) -> Result<(), Error> {
    let result;
    unsafe {
        //if SetConsoleCtrlHandler(Some(console_handler), TRUE) == FALSE
        //{
        //	return Err(format! ("Failed SetConsoleCtrlHandler: {}", error_string(GetLastError() as i32)));
        //}
        result = daemon.holder.exec();
        //if SetConsoleCtrlHandler(Some(console_handler), FALSE) == FALSE
        //{
        //	return Err(format! ("Failed SetConsoleCtrlHandler: {}", error_string(GetLastError() as i32)));
        //}
    }
    result
}

unsafe extern "system" fn signal_handler(sig: libc::c_int) {
    daemon_wrapper(|daemon_static: &mut DaemonHolder| {
        let daemon = &mut *daemon_static.holder;
        return match daemon.holder.take_tx() {
            Some(ref tx) => {
                let _ = tx.send(State::Stop);
            }
            None => (),
        };
    });
}

fn daemon_null() -> *mut DaemonStatic {
    0 as *mut DaemonStatic
}

extern "C" {
    fn raise(sig: libc::c_int) -> libc::c_int;
    fn signal(sig: libc::c_int, handler: *const libc::c_void) -> libc::c_int;
    fn kill(pid: libc::pid_t, sig: libc::c_int) -> libc::c_int;
}