daemon 0.0.6

Library for simple creating 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;
}