runner: wait for signals using poll()

1 files changed, 24 insertions, 11 deletions

diff --git a/crates/runner/src/lib.rs b/crates/runner/src/lib.rs
index 97d8815..51e0e17 100644
--- a/crates/runner/src/lib.rs
+++ b/crates/runner/src/lib.rs
@@ -16,6 +16,7 @@ use std::{
 use capctl::prctl;
 use nix::{
 	errno::Errno,
+	poll,
 	sched::CloneFlags,
 	sys::{signal, signalfd::SignalFd, stat, wait},
 	unistd::{self, Gid, Pid, Uid},
@@ -110,19 +111,31 @@ fn runner(uid: Uid, gid: Gid, socket: UnixSeqpacketConn, _lockfile: File, option
 	.expect("fork()")
 	.0;
 
-	loop {
-		let _signal = sfd.read_signal().expect("read_signal()").unwrap();
-
-		loop {
-			let status = match wait::waitpid(Pid::from_raw(-1), Some(wait::WaitPidFlag::WNOHANG)) {
-				Ok(wait::WaitStatus::StillAlive) | Err(Errno::ECHILD) => break,
-				res => res.expect("waitpid()"),
-			};
-			let pid = status.pid().unwrap();
+	let mut pollfds = [poll::PollFd::new(sfd.as_raw_fd(), poll::PollFlags::POLLIN)];
 
-			if pid == msg_handler {
-				return;
+	loop {
+		poll::poll(&mut pollfds, -1).expect("poll()");
+
+		let events = pollfds[0]
+			.revents()
+			.expect("Unknown events in poll() return");
+		if events.contains(poll::PollFlags::POLLIN) {
+			let _signal = sfd.read_signal().expect("read_signal()").unwrap();
+
+			loop {
+				let status =
+					match wait::waitpid(Pid::from_raw(-1), Some(wait::WaitPidFlag::WNOHANG)) {
+						Ok(wait::WaitStatus::StillAlive) | Err(Errno::ECHILD) => break,
+						res => res.expect("waitpid()"),
+					};
+				let pid = status.pid().unwrap();
+
+				if pid == msg_handler {
+					return;
+				}
 			}
+		} else if events.intersects(!poll::PollFlags::POLLIN) {
+			panic!("Unexpected error status for signal file descriptor");
 		}
 	}
 }