Fix writing timeout events. Check that we only return one timeout event.

crates/test-programs/wasi-tests/src/bin/poll_oneoff.rs

@@ -65,11 +65,17 @@ unsafe fn test_stdin_read() {
             r#type: wasi::EVENTTYPE_CLOCK,
             u: wasi::SubscriptionU { clock },
         },
+        // Make sure that timeout is returned only once even if there are multiple read events
         wasi::Subscription {
             userdata: 1,
             r#type: wasi::EVENTTYPE_FD_READ,
             u: wasi::SubscriptionU { fd_readwrite },
         },
+        wasi::Subscription {
+            userdata: 42,
+            r#type: wasi::EVENTTYPE_FD_READ,
+            u: wasi::SubscriptionU { fd_readwrite },
+        },
     ];
     let out = poll_oneoff_impl(&r#in, 1);
     let event = &out[0];

crates/wasi-common/src/sys/windows/hostcalls_impl/misc.rs

@@ -95,7 +95,7 @@ fn make_rw_event(event: &FdEventData, nbytes: Result<u64>) -> wasi::__wasi_event
     }
 }
 
-fn make_timeout_event(event: &FdEventData, timeout: &ClockEventData) -> wasi::__wasi_event_t {
+fn make_timeout_event(timeout: &ClockEventData) -> wasi::__wasi_event_t {
     wasi::__wasi_event_t {
         userdata: timeout.userdata,
         r#type: wasi::__WASI_EVENTTYPE_CLOCK,
@@ -125,7 +125,12 @@ pub(crate) fn poll_oneoff(
     // With no events to listen, poll_oneoff just becomes a sleep.
     if fd_events.is_empty() {
         match timeout_duration {
-            Some(t) => thread::sleep(t),
+            Some(t) => {
+                thread::sleep(t);
+                let timeout_event = timeout.expect("timeout should be Some");
+                let new_event = make_timeout_event(&timeout_event);
+                events.push(new_event);
+            }
             // `poll` invoked with nfds = 0, timeout = -1 appears to be an infinite sleep
             // Even though the thread is not guanteed to remain parked forever, `poll(2)`
             // mentions that spurious readiness notifications may occur, so it's probably fine
@@ -236,11 +241,9 @@ pub(crate) fn poll_oneoff(
 
         match timeout_occurred {
             Some(timeout_info) => {
-                for event in stdin_events {
-                    let new_event = make_timeout_event(&event, &timeout_info);
+                let new_event = make_timeout_event(&timeout_info);
                 events.push(new_event);
             }
-            }
             None => {
                 // stdin became ready for reading
                 for event in stdin_events {