A signal handler used with sigaction or signal.

Signal handlers have very limited functionality. A signal handler must only call async-signal-safe functions. A list of async-signal-safe functions can be found in signal-safety(7).

In particular, signal handlers should only set a flag using an atomic type (such as std::sync::atomic::AtomicBool) and do nothing else. Any more complex logic should be performed outside the signal handler.

Examples

Catch SIGINT and record it with an atomic flag:

# use std::convert::TryFrom;
# use std::sync::atomic::{AtomicBool, Ordering};
# use nix::sys::signal::{self, Signal, SigHandler};
static SIGNALED: AtomicBool = AtomicBool::new(false);

extern "C" fn handle_sigint(signal: libc::c_int) {
    let signal = Signal::try_from(signal).unwrap();
    SIGNALED.store(signal == Signal::SIGINT, Ordering::Relaxed);
}

fn main() {
    let handler = SigHandler::Handler(handle_sigint);
    unsafe { signal::signal(Signal::SIGINT, handler) }.unwrap();
}