use std::mem; use std::os::unix::io::RawFd; use std::ptr::null_mut; use libc::{self, c_int}; use Result; use errno::Errno; use sys::time::TimeVal; pub use libc::FD_SETSIZE; // FIXME: Change to repr(transparent) once it's stable #[repr(C)] pub struct FdSet(libc::fd_set); impl FdSet { pub fn new() -> FdSet { let mut fdset = unsafe { mem::uninitialized() }; unsafe { libc::FD_ZERO(&mut fdset) }; FdSet(fdset) } pub fn insert(&mut self, fd: RawFd) { unsafe { libc::FD_SET(fd, &mut self.0) }; } pub fn remove(&mut self, fd: RawFd) { unsafe { libc::FD_CLR(fd, &mut self.0) }; } pub fn contains(&mut self, fd: RawFd) -> bool { unsafe { libc::FD_ISSET(fd, &mut self.0) } } pub fn clear(&mut self) { unsafe { libc::FD_ZERO(&mut self.0) }; } /// Finds the highest file descriptor in the set. /// /// Returns `None` if the set is empty. /// /// This can be used to calculate the `nfds` parameter of the [`select`] function. /// /// # Example /// /// ``` /// # extern crate nix; /// # use nix::sys::select::FdSet; /// # fn main() { /// let mut set = FdSet::new(); /// set.insert(4); /// set.insert(9); /// assert_eq!(set.highest(), Some(9)); /// # } /// ``` /// /// [`select`]: fn.select.html pub fn highest(&mut self) -> Option { for i in (0..libc::FD_SETSIZE).rev() { let i = i as RawFd; if unsafe { libc::FD_ISSET(i, self as *mut _ as *mut libc::fd_set) } { return Some(i) } } None } } /// Monitors file descriptors for readiness /// /// Returns the total number of ready file descriptors in all sets. The sets are changed so that all /// file descriptors that are ready for the given operation are set. /// /// When this function returns, `timeout` has an implementation-defined value. /// /// # Parameters /// /// * `nfds`: The highest file descriptor set in any of the passed `FdSet`s, plus 1. If `None`, this /// is calculated automatically by calling [`FdSet::highest`] on all descriptor sets and adding 1 /// to the maximum of that. /// * `readfds`: File descriptors to check for being ready to read. /// * `writefds`: File descriptors to check for being ready to write. /// * `errorfds`: File descriptors to check for pending error conditions. /// * `timeout`: Maximum time to wait for descriptors to become ready (`None` to block /// indefinitely). /// /// # References /// /// [select(2)](http://pubs.opengroup.org/onlinepubs/9699919799/functions/select.html) /// [`FdSet::highest`]: struct.FdSet.html#method.highest pub fn select<'a, N, R, W, E, T>(nfds: N, readfds: R, writefds: W, errorfds: E, timeout: T) -> Result where N: Into>, R: Into>, W: Into>, E: Into>, T: Into>, { let mut readfds = readfds.into(); let mut writefds = writefds.into(); let mut errorfds = errorfds.into(); let timeout = timeout.into(); let nfds = nfds.into().unwrap_or_else(|| { readfds.iter_mut() .chain(writefds.iter_mut()) .chain(errorfds.iter_mut()) .map(|set| set.highest().unwrap_or(-1)) .max() .unwrap_or(-1) + 1 }); let readfds = readfds.map(|set| set as *mut _ as *mut libc::fd_set).unwrap_or(null_mut()); let writefds = writefds.map(|set| set as *mut _ as *mut libc::fd_set).unwrap_or(null_mut()); let errorfds = errorfds.map(|set| set as *mut _ as *mut libc::fd_set).unwrap_or(null_mut()); let timeout = timeout.map(|tv| tv as *mut _ as *mut libc::timeval) .unwrap_or(null_mut()); let res = unsafe { libc::select(nfds, readfds, writefds, errorfds, timeout) }; Errno::result(res) } #[cfg(test)] mod tests { use super::*; use std::os::unix::io::RawFd; use sys::time::{TimeVal, TimeValLike}; use unistd::{write, pipe}; #[test] fn fdset_insert() { let mut fd_set = FdSet::new(); for i in 0..FD_SETSIZE { assert!(!fd_set.contains(i as RawFd)); } fd_set.insert(7); assert!(fd_set.contains(7)); } #[test] fn fdset_remove() { let mut fd_set = FdSet::new(); for i in 0..FD_SETSIZE { assert!(!fd_set.contains(i as RawFd)); } fd_set.insert(7); fd_set.remove(7); for i in 0..FD_SETSIZE { assert!(!fd_set.contains(i as RawFd)); } } #[test] fn fdset_clear() { let mut fd_set = FdSet::new(); fd_set.insert(1); fd_set.insert((FD_SETSIZE / 2) as RawFd); fd_set.insert((FD_SETSIZE - 1) as RawFd); fd_set.clear(); for i in 0..FD_SETSIZE { assert!(!fd_set.contains(i as RawFd)); } } #[test] fn fdset_highest() { let mut set = FdSet::new(); assert_eq!(set.highest(), None); set.insert(0); assert_eq!(set.highest(), Some(0)); set.insert(90); assert_eq!(set.highest(), Some(90)); set.remove(0); assert_eq!(set.highest(), Some(90)); set.remove(90); assert_eq!(set.highest(), None); set.insert(4); set.insert(5); set.insert(7); assert_eq!(set.highest(), Some(7)); } // powerpc-unknown-linux-gnu currently fails on the first `assert_eq` because // `select()` returns a 0 instead of a 1. Since this test has only been run on // qemu, it's unclear if this is a OS or qemu bug. Just disable it on that arch // for now. // FIXME: Fix tests for powerpc and mips // FIXME: Add a link to an upstream qemu bug if there is one #[test] #[cfg_attr(any(target_arch = "powerpc", target_arch = "mips"), ignore)] fn test_select() { let (r1, w1) = pipe().unwrap(); write(w1, b"hi!").unwrap(); let (r2, _w2) = pipe().unwrap(); let mut fd_set = FdSet::new(); fd_set.insert(r1); fd_set.insert(r2); let mut timeout = TimeVal::seconds(10); assert_eq!(1, select(None, &mut fd_set, None, None, &mut timeout).unwrap()); assert!(fd_set.contains(r1)); assert!(!fd_set.contains(r2)); } #[test] #[cfg_attr(any(target_arch = "powerpc", target_arch = "mips"), ignore)] fn test_select_nfds() { let (r1, w1) = pipe().unwrap(); write(w1, b"hi!").unwrap(); let (r2, _w2) = pipe().unwrap(); let mut fd_set = FdSet::new(); fd_set.insert(r1); fd_set.insert(r2); let mut timeout = TimeVal::seconds(10); assert_eq!(1, select(Some(fd_set.highest().unwrap() + 1), &mut fd_set, None, None, &mut timeout).unwrap()); assert!(fd_set.contains(r1)); assert!(!fd_set.contains(r2)); } #[test] #[cfg_attr(any(target_arch = "powerpc", target_arch = "mips"), ignore)] fn test_select_nfds2() { let (r1, w1) = pipe().unwrap(); write(w1, b"hi!").unwrap(); let (r2, _w2) = pipe().unwrap(); let mut fd_set = FdSet::new(); fd_set.insert(r1); fd_set.insert(r2); let mut timeout = TimeVal::seconds(10); assert_eq!(1, select(::std::cmp::max(r1, r2) + 1, &mut fd_set, None, None, &mut timeout).unwrap()); assert!(fd_set.contains(r1)); assert!(!fd_set.contains(r2)); } }