Very simple Rust wrapper around pselect

select.rs

/* Copyright (C) 2017 Andrew Ayer
 *
 * Permission is hereby granted, free of charge, to any person obtaining a
 * copy of this software and associated documentation files (the "Software"),
 * to deal in the Software without restriction, including without limitation
 * the rights to use, copy, modify, merge, publish, distribute, sublicense,
 * and/or sell copies of the Software, and to permit persons to whom the
 * Software is furnished to do so, subject to the following conditions:
 *
 * The above copyright notice and this permission notice shall be included
 * in all copies or substantial portions of the Software.
 *
 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
 * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
 * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL
 * THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR
 * OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE,
 * ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR
 * OTHER DEALINGS IN THE SOFTWARE.
 *
 * Except as contained in this notice, the name(s) of the above copyright
 * holders shall not be used in advertising or otherwise to promote the
 * sale, use or other dealings in this Software without prior written
 * authorization.
 */

extern crate libc;

use std::{io,mem,ptr,time};
use std::os::unix::io::RawFd;

pub struct FdSet(libc::fd_set);

impl FdSet {
	pub fn new() -> FdSet {
		unsafe {
			let mut raw_fd_set = mem::uninitialized::<libc::fd_set>();
			libc::FD_ZERO(&mut raw_fd_set);
			FdSet(raw_fd_set)
		}
	}
	pub fn clear(&mut self, fd: RawFd) {
		unsafe {
			libc::FD_CLR(fd, &mut self.0);
		}
	}
	pub fn set(&mut self, fd: RawFd) {
		unsafe {
			libc::FD_SET(fd, &mut self.0);
		}
	}
	pub fn is_set(&mut self, fd: RawFd) -> bool {
		unsafe {
			libc::FD_ISSET(fd, &mut self.0)
		}
	}
}

pub fn pselect (nfds: libc::c_int,
		readfds: Option<&mut FdSet>,
		writefds: Option<&mut FdSet>,
		errorfds: Option<&mut FdSet>,
		timeout: Option<&libc::timespec>,
		sigmask: Option<&libc::sigset_t>) -> io::Result<usize> {

	fn to_fdset_ptr (opt: Option<&mut FdSet>) -> *mut libc::fd_set {
		match opt {
			None => ptr::null_mut(),
			Some(&mut FdSet(ref mut raw_fd_set)) => raw_fd_set,
		}
	}
	fn to_ptr<T> (opt: Option<&T>) -> *const T {
		match opt {
			None => ptr::null::<T>(),
			Some(p) => p,
		}
	}

	match unsafe {
		libc::pselect(nfds,
			      to_fdset_ptr(readfds),
			      to_fdset_ptr(writefds),
			      to_fdset_ptr(errorfds),
			      to_ptr(timeout),
			      to_ptr(sigmask))
	} {
		-1 => Err(io::Error::last_os_error()),
		res => Ok(res as usize),
	}
}

pub fn make_timespec(duration: time::Duration) -> libc::timespec {
	libc::timespec {
		tv_sec:		duration.as_secs() as i64,
		tv_nsec:	duration.subsec_nanos() as i64,
	}
}