From 916887b18bd68c44be321dd1108a6eeb8b60b6b1 Mon Sep 17 00:00:00 2001
From: John Nunley <dev@notgull.net>
Date: Tue, 16 Jan 2024 12:02:55 -0800
Subject: [PATCH] Add epoll support for Redox (#985)

For now it seems that epoll is the preferred way to access Redox's
underlying polling interface. There are event schemes but until Redox's
syscalls are better integrated with Rustix it's probably not worth it
yet.

cc smol-rs/polling#176

Signed-off-by: John Nunley <dev@notgull.net>
---
 src/backend/libc/conv.rs        |  2 +-
 src/backend/libc/event/epoll.rs | 24 +++++++++++++++++-------
 src/backend/libc/event/mod.rs   |  2 +-
 src/event/mod.rs                |  2 +-
 4 files changed, 20 insertions(+), 10 deletions(-)

diff --git a/src/backend/libc/conv.rs b/src/backend/libc/conv.rs
index 1f9bcaf25..171fc10d8 100644
--- a/src/backend/libc/conv.rs
+++ b/src/backend/libc/conv.rs
@@ -70,7 +70,7 @@ pub(super) fn ret_c_int(raw: c::c_int) -> io::Result<c::c_int> {
     }
 }
 
-#[cfg(linux_kernel)]
+#[cfg(any(linux_kernel, all(target_os = "redox", feature = "event")))]
 #[inline]
 pub(super) fn ret_u32(raw: c::c_int) -> io::Result<u32> {
     if raw == -1 {
diff --git a/src/backend/libc/event/epoll.rs b/src/backend/libc/event/epoll.rs
index 4a7f29b93..6e2ba3c12 100644
--- a/src/backend/libc/event/epoll.rs
+++ b/src/backend/libc/event/epoll.rs
@@ -197,6 +197,8 @@ pub fn add(
             as_mut_ptr(&mut Event {
                 flags: event_flags,
                 data,
+                #[cfg(target_os = "redox")]
+                _pad: 0,
             })
             .cast(),
         ))
@@ -228,6 +230,8 @@ pub fn modify(
             as_mut_ptr(&mut Event {
                 flags: event_flags,
                 data,
+                #[cfg(target_os = "redox")]
+                _pad: 0,
             })
             .cast(),
         ))
@@ -295,13 +299,16 @@ impl<'a> Iterator for Iter<'a> {
 /// A record of an event that occurred.
 #[repr(C)]
 #[cfg_attr(
-    any(
-        all(
-            target_arch = "x86",
-            not(target_env = "musl"),
-            not(target_os = "android"),
-        ),
-        target_arch = "x86_64",
+    all(
+        linux_kernel,
+        any(
+            all(
+                target_arch = "x86",
+                not(target_env = "musl"),
+                not(target_os = "android"),
+            ),
+            target_arch = "x86_64",
+        )
     ),
     repr(packed)
 )]
@@ -311,6 +318,9 @@ pub struct Event {
     pub flags: EventFlags,
     /// User data.
     pub data: EventData,
+
+    #[cfg(target_os = "redox")]
+    _pad: u64,
 }
 
 /// Data associated with an [`Event`]. This can either be a 64-bit integer
diff --git a/src/backend/libc/event/mod.rs b/src/backend/libc/event/mod.rs
index 6aed4612a..a07d06b1a 100644
--- a/src/backend/libc/event/mod.rs
+++ b/src/backend/libc/event/mod.rs
@@ -5,5 +5,5 @@ pub(crate) mod types;
 #[cfg_attr(windows, path = "windows_syscalls.rs")]
 pub(crate) mod syscalls;
 
-#[cfg(linux_kernel)]
+#[cfg(any(linux_kernel, target_os = "redox"))]
 pub mod epoll;
diff --git a/src/event/mod.rs b/src/event/mod.rs
index b6b7f9971..c497febe0 100644
--- a/src/event/mod.rs
+++ b/src/event/mod.rs
@@ -15,7 +15,7 @@ mod poll;
 #[cfg(solarish)]
 pub mod port;
 
-#[cfg(linux_kernel)]
+#[cfg(any(linux_kernel, target_os = "redox"))]
 pub use crate::backend::event::epoll;
 #[cfg(any(
     linux_kernel,