Kill the child processes at once on a second interrupt during the grace period

tests/e2e/forwarding.rs

@@ -1,6 +1,8 @@
 use std::os::unix::process::{CommandExt, ExitStatusExt};
 use std::path::Path;
 use std::process::{Child, Stdio};
+use std::thread;
+use std::time::{Duration, Instant};
 
 use tempfile::TempDir;
 
@@ -113,6 +115,46 @@ fn entrypoint_inherits_no_signalfd() {
     );
 }
 
+#[test]
+fn single_interrupt_keeps_grace_period_for_child_processes() {
+    let dir = TempDir::new().expect("failed to create temp dir");
+    let script = "setsid -f sh -c 'trap \"\" INT; trap \"sleep 0.5; touch cleaned; exit\" TERM; touch ready; sleep 60 & wait' </dev/null >/dev/null 2>&1
+                  until [ -e ready ]; do sleep 0.01; done
+                  : > entrypoint-ready
+                  sleep 60";
+
+    let (_sandbox, mut child) = spawn_sandbox(&["--blacklist"], dir.path(), script);
+    wait_for_file(&dir.path().join("entrypoint-ready"));
+    send_signal(&child, libc::SIGINT);
+    child.wait().unwrap();
+
+    assert!(
+        dir.path().join("cleaned").exists(),
+        "child process did not get its grace period"
+    );
+}
+
+#[test]
+fn interrupt_during_grace_period_kills_child_processes_at_once() {
+    let dir = TempDir::new().expect("failed to create temp dir");
+    let script =
+        "setsid -f sh -c 'trap \"\" TERM; touch ready; sleep 60' </dev/null >/dev/null 2>&1
+                  until [ -e ready ]; do sleep 0.01; done";
+
+    let (_sandbox, mut child) = spawn_sandbox(&["--blacklist"], dir.path(), script);
+    wait_for_file(&dir.path().join("ready"));
+    thread::sleep(Duration::from_millis(300));
+    let interrupted_at = Instant::now();
+    send_signal(&child, libc::SIGINT);
+    child.wait().unwrap();
+
+    assert!(
+        interrupted_at.elapsed() < Duration::from_secs(2),
+        "agent-sandbox waited {:?} after the interrupt",
+        interrupted_at.elapsed()
+    );
+}
+
 fn spawn_sandbox(args: &[&str], dir: &Path, script: &str) -> (Sandbox, Child) {
     let mut sandbox = Sandbox::new(args);
     let child = sandbox