return to toplevel from a long running query after receiving Ctrl-C

src/main.rs

@@ -2,20 +2,38 @@
 extern crate downcast;
 extern crate indexmap;
 #[macro_use]
+extern crate lazy_static;
+extern crate libc;
+extern crate nix;
+#[macro_use]
 extern crate prolog_parser;
 #[macro_use]
 extern crate ref_thread_local;
 extern crate termion;
 
+use nix::sys::signal;
+
 mod prolog;
 
 use prolog::machine::*;
 use prolog::read::*;
 
+use std::sync::atomic::Ordering;
+
 #[cfg(test)]
 mod tests;
 
+extern fn handle_sigint(signal: libc::c_int) {
+    let signal = signal::Signal::from_c_int(signal).unwrap();
+    if signal == signal::Signal::SIGINT {
+	INTERRUPT.store(true, Ordering::Relaxed);
+    }
+}
+
 fn main() {
-    let mut wam = Machine::new(readline::input_stream());  
+    let handler = signal::SigHandler::Handler(handle_sigint);
+    unsafe { signal::signal(signal::Signal::SIGINT, handler) }.unwrap();
+
+    let mut wam = Machine::new(readline::input_stream());
     wam.run_top_level();
 }