path: root/src/sys/signal.rs

// Portions of this file are Copyright 2014 The Rust Project Developers.
// See http://rust-lang.org/COPYRIGHT.

use libc;
use {Errno, Error, Result};
use std::fmt;
use std::fmt::Debug;
use std::mem;
#[cfg(any(target_os = "dragonfly", target_os = "freebsd"))]
use std::os::unix::io::RawFd;
use std::ptr;

// Currently there is only one definition of c_int in libc, as well as only one
// type for signal constants.
// We would prefer to use the libc::c_int alias in the repr attribute. Unfortunately
// this is not (yet) possible.
#[derive(Clone, Copy, Debug, Eq, PartialEq)]
#[repr(i32)]
pub enum Signal {
    SIGHUP = libc::SIGHUP,
    SIGINT = libc::SIGINT,
    SIGQUIT = libc::SIGQUIT,
    SIGILL = libc::SIGILL,
    SIGTRAP = libc::SIGTRAP,
    SIGABRT = libc::SIGABRT,
    SIGBUS = libc::SIGBUS,
    SIGFPE = libc::SIGFPE,
    SIGKILL = libc::SIGKILL,
    SIGUSR1 = libc::SIGUSR1,
    SIGSEGV = libc::SIGSEGV,
    SIGUSR2 = libc::SIGUSR2,
    SIGPIPE = libc::SIGPIPE,
    SIGALRM = libc::SIGALRM,
    SIGTERM = libc::SIGTERM,
    #[cfg(all(any(target_os = "linux", target_os = "android", target_os = "emscripten"), not(target_arch = "mips")))]
    SIGSTKFLT = libc::SIGSTKFLT,
    SIGCHLD = libc::SIGCHLD,
    SIGCONT = libc::SIGCONT,
    SIGSTOP = libc::SIGSTOP,
    SIGTSTP = libc::SIGTSTP,
    SIGTTIN = libc::SIGTTIN,
    SIGTTOU = libc::SIGTTOU,
    SIGURG = libc::SIGURG,
    SIGXCPU = libc::SIGXCPU,
    SIGXFSZ = libc::SIGXFSZ,
    SIGVTALRM = libc::SIGVTALRM,
    SIGPROF = libc::SIGPROF,
    SIGWINCH = libc::SIGWINCH,
    SIGIO = libc::SIGIO,
    #[cfg(any(target_os = "linux", target_os = "android", target_os = "emscripten"))]
    SIGPWR = libc::SIGPWR,
    SIGSYS = libc::SIGSYS,
    #[cfg(not(any(target_os = "linux", target_os = "android", target_os = "emscripten")))]
    SIGEMT = libc::SIGEMT,
    #[cfg(not(any(target_os = "linux", target_os = "android", target_os = "emscripten")))]
    SIGINFO = libc::SIGINFO,
}

pub use self::Signal::*;

#[cfg(all(any(target_os = "linux", target_os = "android", target_os = "emscripten"), not(target_arch = "mips")))]
const SIGNALS: [Signal; 31] = [
    SIGHUP,
    SIGINT,
    SIGQUIT,
    SIGILL,
    SIGTRAP,
    SIGABRT,
    SIGBUS,
    SIGFPE,
    SIGKILL,
    SIGUSR1,
    SIGSEGV,
    SIGUSR2,
    SIGPIPE,
    SIGALRM,
    SIGTERM,
    SIGSTKFLT,
    SIGCHLD,
    SIGCONT,
    SIGSTOP,
    SIGTSTP,
    SIGTTIN,
    SIGTTOU,
    SIGURG,
    SIGXCPU,
    SIGXFSZ,
    SIGVTALRM,
    SIGPROF,
    SIGWINCH,
    SIGIO,
    SIGPWR,
    SIGSYS];
#[cfg(all(any(target_os = "linux", target_os = "android", target_os = "emscripten"), target_arch = "mips"))]
const SIGNALS: [Signal; 30] = [
    SIGHUP,
    SIGINT,
    SIGQUIT,
    SIGILL,
    SIGTRAP,
    SIGABRT,
    SIGBUS,
    SIGFPE,
    SIGKILL,
    SIGUSR1,
    SIGSEGV,
    SIGUSR2,
    SIGPIPE,
    SIGALRM,
    SIGTERM,
    SIGCHLD,
    SIGCONT,
    SIGSTOP,
    SIGTSTP,
    SIGTTIN,
    SIGTTOU,
    SIGURG,
    SIGXCPU,
    SIGXFSZ,
    SIGVTALRM,
    SIGPROF,
    SIGWINCH,
    SIGIO,
    SIGPWR,
    SIGSYS];
#[cfg(not(any(target_os = "linux", target_os = "android", target_os = "emscripten")))]
const SIGNALS: [Signal; 31] = [
    SIGHUP,
    SIGINT,
    SIGQUIT,
    SIGILL,
    SIGTRAP,
    SIGABRT,
    SIGBUS,
    SIGFPE,
    SIGKILL,
    SIGUSR1,
    SIGSEGV,
    SIGUSR2,
    SIGPIPE,
    SIGALRM,
    SIGTERM,
    SIGCHLD,
    SIGCONT,
    SIGSTOP,
    SIGTSTP,
    SIGTTIN,
    SIGTTOU,
    SIGURG,
    SIGXCPU,
    SIGXFSZ,
    SIGVTALRM,
    SIGPROF,
    SIGWINCH,
    SIGIO,
    SIGSYS,
    SIGEMT,
    SIGINFO];

pub const NSIG: libc::c_int = 32;

pub struct SignalIterator {
    next: usize,
}

impl Iterator for SignalIterator {
    type Item = Signal;

    fn next(&mut self) -> Option<Signal> {
        if self.next < SIGNALS.len() {
            let next_signal = SIGNALS[self.next];
            self.next += 1;
            Some(next_signal)
        } else {
            None
        }
    }
}

impl Signal {
    pub fn iterator() -> SignalIterator {
        SignalIterator{next: 0}
    }

    // We do not implement the From trait, because it is supposed to be infallible.
    // With Rust RFC 1542 comes the appropriate trait TryFrom. Once it is
    // implemented, we'll replace this function.
    #[inline]
    pub fn from_c_int(signum: libc::c_int) -> Result<Signal> {
        match 0 < signum && signum < NSIG {
            true => Ok(unsafe { mem::transmute(signum) }),
            false => Err(Error::invalid_argument()),
        }
    }
}

pub const SIGIOT : Signal = SIGABRT;
pub const SIGPOLL : Signal = SIGIO;
pub const SIGUNUSED : Signal = SIGSYS;

#[cfg(not(target_os = "android"))]
libc_bitflags!{
    pub flags SaFlags: libc::c_int {
        SA_NOCLDSTOP,
        SA_NOCLDWAIT,
        SA_NODEFER,
        SA_ONSTACK,
        SA_RESETHAND,
        SA_RESTART,
        SA_SIGINFO,
    }
}

// On 64-bit android, sa_flags is c_uint while on 32-bit android, it is
// c_ulong.
// FIXME: https://github.com/rust-lang/libc/pull/511
#[cfg(all(target_os = "android", target_pointer_width = "32"))]
libc_bitflags!{
    pub flags SaFlags: libc::c_ulong {
        SA_NOCLDSTOP as libc::c_ulong,
        SA_NOCLDWAIT as libc::c_ulong,
        SA_NODEFER as libc::c_ulong,
        SA_ONSTACK as libc::c_ulong,
        SA_RESETHAND as libc::c_ulong,
        SA_RESTART as libc::c_ulong,
        SA_SIGINFO as libc::c_ulong,
    }
}

#[cfg(all(target_os = "android", target_pointer_width = "64"))]
libc_bitflags!{
    pub flags SaFlags: libc::c_uint {
        SA_NOCLDSTOP as libc::c_uint,
        SA_NOCLDWAIT as libc::c_uint,
        SA_NODEFER as libc::c_uint,
        SA_ONSTACK as libc::c_uint,
        SA_RESETHAND as libc::c_uint,
        SA_RESTART as libc::c_uint,
        SA_SIGINFO as libc::c_uint,
    }
}

#[repr(i32)]
#[derive(Clone, Copy, PartialEq)]
pub enum SigmaskHow {
    SIG_BLOCK   = libc::SIG_BLOCK,
    SIG_UNBLOCK = libc::SIG_UNBLOCK,
    SIG_SETMASK = libc::SIG_SETMASK,
}

#[derive(Clone, Copy)]
pub struct SigSet {
    sigset: libc::sigset_t
}


impl SigSet {
    pub fn all() -> SigSet {
        let mut sigset: libc::sigset_t = unsafe { mem::uninitialized() };
        let _ = unsafe { libc::sigfillset(&mut sigset as *mut libc::sigset_t) };

        SigSet { sigset: sigset }
    }

    pub fn empty() -> SigSet {
        let mut sigset: libc::sigset_t = unsafe { mem::uninitialized() };
        let _ = unsafe { libc::sigemptyset(&mut sigset as *mut libc::sigset_t) };

        SigSet { sigset: sigset }
    }

    pub fn add(&mut self, signal: Signal) {
        unsafe { libc::sigaddset(&mut self.sigset as *mut libc::sigset_t, signal as libc::c_int) };
    }

    pub fn clear(&mut self) {
        unsafe { libc::sigemptyset(&mut self.sigset as *mut libc::sigset_t) };
    }

    pub fn remove(&mut self, signal: Signal) {
        unsafe { libc::sigdelset(&mut self.sigset as *mut libc::sigset_t, signal as libc::c_int) };
    }

    pub fn contains(&self, signal: Signal) -> bool {
        let res = unsafe { libc::sigismember(&self.sigset as *const libc::sigset_t, signal as libc::c_int) };

        match res {
            1 => true,
            0 => false,
            _ => unreachable!("unexpected value from sigismember"),
        }
    }

    pub fn extend(&mut self, other: &SigSet) {
        for signal in Signal::iterator() {
            if other.contains(signal) {
                self.add(signal);
            }
        }
    }

    /// Gets the currently blocked (masked) set of signals for the calling thread.
    pub fn thread_get_mask() -> Result<SigSet> {
        let mut oldmask: SigSet = unsafe { mem::uninitialized() };
        try!(pthread_sigmask(SigmaskHow::SIG_SETMASK, None, Some(&mut oldmask)));
        Ok(oldmask)
    }

    /// Sets the set of signals as the signal mask for the calling thread.
    pub fn thread_set_mask(&self) -> Result<()> {
        pthread_sigmask(SigmaskHow::SIG_SETMASK, Some(self), None)
    }

    /// Adds the set of signals to the signal mask for the calling thread.
    pub fn thread_block(&self) -> Result<()> {
        pthread_sigmask(SigmaskHow::SIG_BLOCK, Some(self), None)
    }

    /// Removes the set of signals from the signal mask for the calling thread.
    pub fn thread_unblock(&self) -> Result<()> {
        pthread_sigmask(SigmaskHow::SIG_UNBLOCK, Some(self), None)
    }

    /// Sets the set of signals as the signal mask, and returns the old mask.
    pub fn thread_swap_mask(&self, how: SigmaskHow) -> Result<SigSet> {
        let mut oldmask: SigSet = unsafe { mem::uninitialized() };
        try!(pthread_sigmask(how, Some(self), Some(&mut oldmask)));
        Ok(oldmask)
    }

    /// Suspends execution of the calling thread until one of the signals in the
    /// signal mask becomes pending, and returns the accepted signal.
    pub fn wait(&self) -> Result<Signal> {
        let mut signum: libc::c_int = unsafe { mem::uninitialized() };
        let res = unsafe { libc::sigwait(&self.sigset as *const libc::sigset_t, &mut signum) };

        Errno::result(res).map(|_| Signal::from_c_int(signum).unwrap())
    }
}

impl AsRef<libc::sigset_t> for SigSet {
    fn as_ref(&self) -> &libc::sigset_t {
        &self.sigset
    }
}

#[allow(unknown_lints)]
#[derive(Debug, Clone, Copy, PartialEq)]
pub enum SigHandler {
    SigDfl,
    SigIgn,
    Handler(extern fn(libc::c_int)),
    SigAction(extern fn(libc::c_int, *mut libc::siginfo_t, *mut libc::c_void))
}

pub struct SigAction {
    sigaction: libc::sigaction
}

impl SigAction {
    /// This function will set or unset the flag `SA_SIGINFO` depending on the
    /// type of the `handler` argument.
    pub fn new(handler: SigHandler, flags: SaFlags, mask: SigSet) -> SigAction {
        let mut s = unsafe { mem::uninitialized::<libc::sigaction>() };
        s.sa_sigaction = match handler {
            SigHandler::SigDfl => unsafe { mem::transmute(libc::SIG_DFL) },
            SigHandler::SigIgn => unsafe { mem::transmute(libc::SIG_IGN) },
            SigHandler::Handler(f) => unsafe { mem::transmute(f) },
            SigHandler::SigAction(f) => unsafe { mem::transmute(f) },
        };
        s.sa_flags = match handler {
            SigHandler::SigAction(_) => (flags | SA_SIGINFO).bits(),
            _ => (flags - SA_SIGINFO).bits(),
        };
        s.sa_mask = mask.sigset;

        SigAction { sigaction: s }
    }

    pub fn flags(&self) -> SaFlags {
        SaFlags::from_bits(self.sigaction.sa_flags).unwrap()
    }

    pub fn mask(&self) -> SigSet {
        SigSet { sigset: self.sigaction.sa_mask }
    }

    pub fn handler(&self) -> SigHandler {
        match self.sigaction.sa_sigaction {
            libc::SIG_DFL => SigHandler::SigDfl,
            libc::SIG_IGN => SigHandler::SigIgn,
            f if self.flags().contains(SA_SIGINFO) =>
                SigHandler::SigAction( unsafe { mem::transmute(f) } ),
            f => SigHandler::Handler( unsafe { mem::transmute(f) } ),
        }
    }
}

pub unsafe fn sigaction(signal: Signal, sigaction: &SigAction) -> Result<SigAction> {
    let mut oldact = mem::uninitialized::<libc::sigaction>();

    let res =
        libc::sigaction(signal as libc::c_int, &sigaction.sigaction as *const libc::sigaction, &mut oldact as *mut libc::sigaction);

    Errno::result(res).map(|_| SigAction { sigaction: oldact })
}

/// Manages the signal mask (set of blocked signals) for the calling thread.
///
/// If the `set` parameter is `Some(..)`, then the signal mask will be updated with the signal set.
/// The `how` flag decides the type of update. If `set` is `None`, `how` will be ignored,
/// and no modification will take place.
///
/// If the 'oldset' parameter is `Some(..)` then the current signal mask will be written into it.
///
/// If both `set` and `oldset` is `Some(..)`, the current signal mask will be written into oldset,
/// and then it will be updated with `set`.
///
/// If both `set` and `oldset` is None, this function is a no-op.
///
/// For more information, visit the [pthread_sigmask](http://man7.org/linux/man-pages/man3/pthread_sigmask.3.html),
/// or [sigprocmask](http://man7.org/linux/man-pages/man2/sigprocmask.2.html) man pages.
pub fn pthread_sigmask(how: SigmaskHow,
                       set: Option<&SigSet>,
                       oldset: Option<&mut SigSet>) -> Result<()> {
    if set.is_none() && oldset.is_none() {
        return Ok(())
    }

    let res = unsafe {
        // if set or oldset is None, pass in null pointers instead
        libc::pthread_sigmask(how as libc::c_int,
                             set.map_or_else(|| ptr::null::<libc::sigset_t>(),
                                             |s| &s.sigset as *const libc::sigset_t),
                             oldset.map_or_else(|| ptr::null_mut::<libc::sigset_t>(),
                                                |os| &mut os.sigset as *mut libc::sigset_t))
    };

    Errno::result(res).map(drop)
}

pub fn kill<T: Into<Option<Signal>>>(pid: ::unistd::Pid, signal: T) -> Result<()> {
    let res = unsafe { libc::kill(pid.into(),
                                  match signal.into() {
                                      Some(s) => s as libc::c_int,
                                      None => 0,
                                  }) };

    Errno::result(res).map(drop)
}

pub fn raise(signal: Signal) -> Result<()> {
    let res = unsafe { libc::raise(signal as libc::c_int) };

    Errno::result(res).map(drop)
}


#[cfg(target_os = "freebsd")]
pub type type_of_thread_id = libc::lwpid_t;
#[cfg(target_os = "linux")]
pub type type_of_thread_id = libc::pid_t;

/// Used to request asynchronous notification of certain events, for example,
/// with POSIX AIO, POSIX message queues, and POSIX timers.
// sigval is actually a union of a int and a void*.  But it's never really used
// as a pointer, because neither libc nor the kernel ever dereference it.  nix
// therefore presents it as an intptr_t, which is how kevent uses it.
#[derive(Clone, Copy, Debug, PartialEq)]
pub enum SigevNotify {
    /// No notification will be delivered
    SigevNone,
    /// The signal given by `signal` will be delivered to the process.  The
    /// value in `si_value` will be present in the `si_value` field of the
    /// `siginfo_t` structure of the queued signal.
    SigevSignal { signal: Signal, si_value: libc::intptr_t },
    // Note: SIGEV_THREAD is not implemented because libc::sigevent does not
    // expose a way to set the union members needed by SIGEV_THREAD.
    /// A new `kevent` is posted to the kqueue `kq`.  The `kevent`'s `udata`
    /// field will contain the value in `udata`.
    #[cfg(any(target_os = "dragonfly", target_os = "freebsd"))]
    SigevKevent { kq: RawFd, udata: libc::intptr_t },
    /// The signal `signal` is queued to the thread whose LWP ID is given in
    /// `thread_id`.  The value stored in `si_value` will be present in the
    /// `si_value` of the `siginfo_t` structure of the queued signal.
    #[cfg(any(target_os = "freebsd", target_os = "linux"))]
    SigevThreadId { signal: Signal, thread_id: type_of_thread_id,
                    si_value: libc::intptr_t },
}

/// Used to request asynchronous notification of the completion of certain
/// events, such as POSIX AIO and timers.
#[repr(C)]
pub struct SigEvent {
    sigevent: libc::sigevent
}

impl SigEvent {
    // Note: this constructor does not allow the user to set the
    // sigev_notify_kevent_flags field.  That's considered ok because on FreeBSD
    // at least those flags don't do anything useful.  That field is part of a
    // union that shares space with the more genuinely useful
    // Note: This constructor also doesn't allow the caller to set the
    // sigev_notify_function or sigev_notify_attributes fields, which are
    // required for SIGEV_THREAD.  That's considered ok because on no operating
    // system is SIGEV_THREAD the most efficient way to deliver AIO
    // notification.  FreeBSD and Dragonfly programs should prefer SIGEV_KEVENT.
    // Linux, Solaris, and portable programs should prefer SIGEV_THREAD_ID or
    // SIGEV_SIGNAL.  That field is part of a union that shares space with the
    // more genuinely useful sigev_notify_thread_id
    pub fn new(sigev_notify: SigevNotify) -> SigEvent {
        let mut sev = unsafe { mem::zeroed::<libc::sigevent>()};
        sev.sigev_notify = match sigev_notify {
            SigevNotify::SigevNone => libc::SIGEV_NONE,
            SigevNotify::SigevSignal{..} => libc::SIGEV_SIGNAL,
            #[cfg(any(target_os = "dragonfly", target_os = "freebsd"))]
            SigevNotify::SigevKevent{..} => libc::SIGEV_KEVENT,
            #[cfg(target_os = "freebsd")]
            SigevNotify::SigevThreadId{..} => libc::SIGEV_THREAD_ID,
            #[cfg(all(target_os = "linux", target_env = "gnu", not(target_arch = "mips")))]
            SigevNotify::SigevThreadId{..} => libc::SIGEV_THREAD_ID,
            #[cfg(any(all(target_os = "linux", target_env = "musl"), target_arch = "mips"))]
            SigevNotify::SigevThreadId{..} => 4  // No SIGEV_THREAD_ID defined
        };
        sev.sigev_signo = match sigev_notify {
            SigevNotify::SigevSignal{ signal, .. } => signal as ::c_int,
            #[cfg(any(target_os = "dragonfly", target_os = "freebsd"))]
            SigevNotify::SigevKevent{ kq, ..} => kq,
            #[cfg(any(target_os = "linux", target_os = "freebsd"))]
            SigevNotify::SigevThreadId{ signal, .. } => signal as ::c_int,
            _ => 0
        };
        sev.sigev_value.sival_ptr = match sigev_notify {
            SigevNotify::SigevNone => ptr::null_mut::<libc::c_void>(),
            SigevNotify::SigevSignal{ si_value, .. } => si_value as *mut ::c_void,
            #[cfg(any(target_os = "dragonfly", target_os = "freebsd"))]
            SigevNotify::SigevKevent{ udata, .. } => udata as *mut ::c_void,
            #[cfg(any(target_os = "linux", target_os = "freebsd"))]
            SigevNotify::SigevThreadId{ si_value, .. } => si_value as *mut ::c_void,
        };
        SigEvent::set_tid(&mut sev, &sigev_notify);
        SigEvent{sigevent: sev}
    }

    #[cfg(any(target_os = "linux", target_os = "freebsd"))]
    fn set_tid(sev: &mut libc::sigevent, sigev_notify: &SigevNotify) {
        sev.sigev_notify_thread_id = match sigev_notify {
            &SigevNotify::SigevThreadId { thread_id, .. } => thread_id,
            _ => 0 as type_of_thread_id
        };
    }

    #[cfg(not(any(target_os = "freebsd", target_os = "linux")))]
    fn set_tid(_sev: &mut libc::sigevent, _sigev_notify: &SigevNotify) {
    }

    pub fn sigevent(&self) -> libc::sigevent {
        self.sigevent
    }
}

impl Debug for SigEvent {
    #[cfg(any(target_os = "linux", target_os = "freebsd"))]
    fn fmt(&self, fmt: &mut fmt::Formatter) -> fmt::Result {
        fmt.debug_struct("SigEvent")
            .field("sigev_notify", &self.sigevent.sigev_notify)
            .field("sigev_signo", &self.sigevent.sigev_signo)
            .field("sigev_value", &self.sigevent.sigev_value.sival_ptr)
            .field("sigev_notify_thread_id",
                    &self.sigevent.sigev_notify_thread_id)
            .finish()
    }

    #[cfg(not(any(target_os = "linux", target_os = "freebsd")))]
    fn fmt(&self, fmt: &mut fmt::Formatter) -> fmt::Result {
        fmt.debug_struct("SigEvent")
            .field("sigev_notify", &self.sigevent.sigev_notify)
            .field("sigev_signo", &self.sigevent.sigev_signo)
            .field("sigev_value", &self.sigevent.sigev_value.sival_ptr)
            .finish()
    }
}

impl<'a> From<&'a libc::sigevent> for SigEvent {
    fn from(sigevent: &libc::sigevent) -> Self {
        SigEvent{ sigevent: sigevent.clone() }
    }
}

#[cfg(test)]
mod tests {
    use super::*;

    #[test]
    fn test_contains() {
        let mut mask = SigSet::empty();
        mask.add(SIGUSR1);

        assert!(mask.contains(SIGUSR1));
        assert!(!mask.contains(SIGUSR2));

        let all = SigSet::all();
        assert!(all.contains(SIGUSR1));
        assert!(all.contains(SIGUSR2));
    }

    #[test]
    fn test_clear() {
        let mut set = SigSet::all();
        set.clear();
        for signal in Signal::iterator() {
            assert!(!set.contains(signal));
        }
    }

    #[test]
    fn test_extend() {
        let mut one_signal = SigSet::empty();
        one_signal.add(SIGUSR1);

        let mut two_signals = SigSet::empty();
        two_signals.add(SIGUSR2);
        two_signals.extend(&one_signal);

        assert!(two_signals.contains(SIGUSR1));
        assert!(two_signals.contains(SIGUSR2));
    }

    // This test doesn't actually test get_mask functionality, see the set_mask test for that.
    #[test]
    fn test_thread_signal_get_mask() {
        assert!(SigSet::thread_get_mask().is_ok());
    }

    #[test]
    fn test_thread_signal_set_mask() {
        let prev_mask = SigSet::thread_get_mask().expect("Failed to get existing signal mask!");

        let mut test_mask = prev_mask;
        test_mask.add(SIGUSR1);

        assert!(test_mask.thread_set_mask().is_ok());
        let new_mask = SigSet::thread_get_mask().expect("Failed to get new mask!");

        assert!(new_mask.contains(SIGUSR1));
        assert!(!new_mask.contains(SIGUSR2));

        prev_mask.thread_set_mask().expect("Failed to revert signal mask!");
    }

    #[test]
    fn test_thread_signal_block() {
        let mut mask = SigSet::empty();
        mask.add(SIGUSR1);

        assert!(mask.thread_block().is_ok());

        assert!(SigSet::thread_get_mask().unwrap().contains(SIGUSR1));
    }

    #[test]
    fn test_thread_signal_unblock() {
        let mut mask = SigSet::empty();
        mask.add(SIGUSR1);

        assert!(mask.thread_unblock().is_ok());

        assert!(!SigSet::thread_get_mask().unwrap().contains(SIGUSR1));
    }

    #[test]
    fn test_thread_signal_swap() {
        let mut mask = SigSet::empty();
        mask.add(SIGUSR1);
        mask.thread_block().unwrap();

        assert!(SigSet::thread_get_mask().unwrap().contains(SIGUSR1));

        let mut mask2 = SigSet::empty();
        mask2.add(SIGUSR2);

        let oldmask = mask2.thread_swap_mask(SigmaskHow::SIG_SETMASK).unwrap();

        assert!(oldmask.contains(SIGUSR1));
        assert!(!oldmask.contains(SIGUSR2));

        assert!(SigSet::thread_get_mask().unwrap().contains(SIGUSR2));
    }

    #[test]
    fn test_sigaction() {
        use libc;

        extern fn test_sigaction_handler(_: libc::c_int) {}
        extern fn test_sigaction_action(_: libc::c_int,
            _: *mut libc::siginfo_t, _: *mut libc::c_void) {}

        let handler_sig = SigHandler::Handler(test_sigaction_handler);

        let flags = SA_ONSTACK | SA_RESTART | SA_SIGINFO;

        let mut mask = SigSet::empty();
        mask.add(SIGUSR1);

        let action_sig = SigAction::new(handler_sig, flags, mask);

        assert_eq!(action_sig.flags(), SA_ONSTACK | SA_RESTART);
        assert_eq!(action_sig.handler(), handler_sig);

        mask = action_sig.mask();
        assert!(mask.contains(SIGUSR1));
        assert!(!mask.contains(SIGUSR2));

        let handler_act = SigHandler::SigAction(test_sigaction_action);
        let action_act = SigAction::new(handler_act, flags, mask);
        assert_eq!(action_act.handler(), handler_act);

        let action_dfl = SigAction::new(SigHandler::SigDfl, flags, mask);
        assert_eq!(action_dfl.handler(), SigHandler::SigDfl);

        let action_ign = SigAction::new(SigHandler::SigIgn, flags, mask);
        assert_eq!(action_ign.handler(), SigHandler::SigIgn);
    }

    // TODO(#251): Re-enable after figuring out flakiness.
    #[cfg(not(any(target_os = "macos", target_os = "ios")))]
    #[test]
    fn test_sigwait() {
        let mut mask = SigSet::empty();
        mask.add(SIGUSR1);
        mask.add(SIGUSR2);
        mask.thread_block().unwrap();

        raise(SIGUSR1).unwrap();
        assert_eq!(mask.wait().unwrap(), SIGUSR1);
    }
}