From 1cf328476bb210cc0c8e64c61ddfea2b5b988845 Mon Sep 17 00:00:00 2001
From: Nicholas Bishop <nbishop@nbishop.net>
Date: Wed, 7 Aug 2024 00:44:57 -0400
Subject: [PATCH] boot: Add freestanding check_event

Also add corresponding test to uefi-test-runner.
---
 uefi-test-runner/src/boot/misc.rs | 13 +++++++++++++
 uefi/src/boot.rs                  | 25 +++++++++++++++++++++++++
 2 files changed, 38 insertions(+)

diff --git a/uefi-test-runner/src/boot/misc.rs b/uefi-test-runner/src/boot/misc.rs
index f78a8ea97..5768320e4 100644
--- a/uefi-test-runner/src/boot/misc.rs
+++ b/uefi-test-runner/src/boot/misc.rs
@@ -17,6 +17,7 @@ pub fn test(st: &SystemTable<Boot>) {
     info!("Testing timer...");
     test_timer(bt);
     info!("Testing events...");
+    test_check_event_freestanding();
     test_event_callback(bt);
     test_callback_with_ctx(bt);
     info!("Testing watchdog...");
@@ -35,6 +36,18 @@ fn test_tpl() {
     let _guard = unsafe { boot::raise_tpl(Tpl::NOTIFY) };
 }
 
+fn test_check_event_freestanding() {
+    extern "efiapi" fn callback(_event: Event, _ctx: Option<NonNull<c_void>>) {
+        info!("Callback triggered by check_event");
+    }
+
+    let event =
+        unsafe { boot::create_event(EventType::NOTIFY_WAIT, Tpl::CALLBACK, Some(callback), None) }
+            .unwrap();
+    let is_signaled = boot::check_event(event).unwrap();
+    assert!(!is_signaled);
+}
+
 fn test_timer(bt: &BootServices) {
     let timer_event = unsafe { bt.create_event(EventType::TIMER, Tpl::APPLICATION, None, None) }
         .expect("Failed to create TIMER event");
diff --git a/uefi/src/boot.rs b/uefi/src/boot.rs
index 2de6cf680..dbf4b6c73 100644
--- a/uefi/src/boot.rs
+++ b/uefi/src/boot.rs
@@ -208,6 +208,31 @@ pub unsafe fn create_event(
     )
 }
 
+/// Checks to see if an event is signaled, without blocking execution to wait for it.
+///
+/// Returns `Ok(true)` if the event is in the signaled state or `Ok(false)`
+/// if the event is not in the signaled state.
+///
+/// # Errors
+///
+/// Note: Instead of returning [`Status::NOT_READY`] as listed in the UEFI
+/// Specification, this function will return `Ok(false)`.
+///
+/// * [`Status::INVALID_PARAMETER`]: `event` is of type [`NOTIFY_SIGNAL`].
+///
+/// [`NOTIFY_SIGNAL`]: EventType::NOTIFY_SIGNAL
+pub fn check_event(event: Event) -> Result<bool> {
+    let bt = boot_services_raw_panicking();
+    let bt = unsafe { bt.as_ref() };
+
+    let status = unsafe { (bt.check_event)(event.as_ptr()) };
+    match status {
+        Status::SUCCESS => Ok(true),
+        Status::NOT_READY => Ok(false),
+        _ => Err(status.into()),
+    }
+}
+
 /// Connect one or more drivers to a controller.
 ///
 /// Usually one disconnects and then reconnects certain drivers