From 04463bf78cf86d6e7a9236e911de00db9096372b Mon Sep 17 00:00:00 2001
From: Elinor Berger <elinor@safaradeg.net>
Date: Fri, 6 Oct 2023 00:09:51 +0200
Subject: [PATCH] Implement `AsRawFd`/`AsFd` for `EventLoop<'l, Data>`

This should allow inserting one `EventLoop` into another.
---
 CHANGELOG.md      |  1 +
 src/loop_logic.rs | 31 ++++++++++++++++++++++++++++++-
 src/sys.rs        |  2 +-
 3 files changed, 32 insertions(+), 2 deletions(-)

diff --git a/CHANGELOG.md b/CHANGELOG.md
index f11f1f19..27919f92 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -5,6 +5,7 @@
 #### Additions
 
 - `Token` and `RegistrationToken` are now invalidated when the event source they represent is removed from the event loop.
+- Implement `AsRawFd` and `AsFd` for `EventLoop<'l, Data>`
 
 #### Bugfixes
 
diff --git a/src/loop_logic.rs b/src/loop_logic.rs
index 1db8a534..58bf4071 100644
--- a/src/loop_logic.rs
+++ b/src/loop_logic.rs
@@ -1,6 +1,6 @@
 use std::cell::{Cell, RefCell};
 use std::fmt::Debug;
-use std::os::unix::io::AsFd;
+use std::os::unix::io::{AsFd, AsRawFd, BorrowedFd, RawFd};
 use std::rc::Rc;
 use std::sync::atomic::{AtomicBool, Ordering};
 use std::sync::Arc;
@@ -11,6 +11,7 @@ use std::{io, slice};
 use std::future::Future;
 
 use log::trace;
+use polling::Poller;
 
 use crate::list::{SourceEntry, SourceList};
 use crate::sources::{Dispatcher, EventSource, Idle, IdleDispatcher};
@@ -286,6 +287,7 @@ impl<'l, Data> LoopHandle<'l, Data> {
 ///
 /// This loop can host several event sources, that can be dynamically added or removed.
 pub struct EventLoop<'l, Data> {
+    poller: Arc<Poller>,
     handle: LoopHandle<'l, Data>,
     signals: Arc<Signals>,
     // A caching vector for synthetic poll events
@@ -315,6 +317,7 @@ impl<'l, Data> EventLoop<'l, Data> {
     /// Fails if the initialization of the polling system failed.
     pub fn try_new() -> crate::Result<Self> {
         let poll = Poll::new()?;
+        let poller = poll.poller.clone();
         let handle = LoopHandle {
             inner: Rc::new(LoopInner {
                 poll: RefCell::new(poll),
@@ -332,6 +335,7 @@ impl<'l, Data> EventLoop<'l, Data> {
                 #[cfg(feature = "block_on")]
                 future_ready: AtomicBool::new(false),
             }),
+            poller,
             synthetic_events: vec![],
         })
     }
@@ -660,6 +664,31 @@ impl<'l, Data> EventLoop<'l, Data> {
     }
 }
 
+impl<'l, Data> AsRawFd for EventLoop<'l, Data> {
+    /// Get the underlying raw-fd of the poller.
+    ///
+    /// This could be used to create [`Generic`] source out of the current loop
+    /// and inserting into some other [`EventLoop`]. It's recommended to clone `fd`
+    /// before doing so.
+    ///
+    /// [`Generic`]: crate::generic::Generic
+    fn as_raw_fd(&self) -> RawFd {
+        self.poller.as_raw_fd()
+    }
+}
+
+impl<'l, Data> AsFd for EventLoop<'l, Data> {
+    /// Get the underlying fd of the poller.
+    ///
+    /// This could be used to create [`Generic`] source out of the current loop
+    /// and inserting into some other [`EventLoop`].
+    ///
+    /// [`Generic`]: crate::generic::Generic
+    fn as_fd(&self) -> BorrowedFd<'_> {
+        self.poller.as_fd()
+    }
+}
+
 #[derive(Clone, Debug)]
 /// The EventIterator is an `Iterator` over the events relevant to a particular source
 /// This type is used in the [`EventSource::before_handle_events`] methods for
diff --git a/src/sys.rs b/src/sys.rs
index d7a473c3..2efe6ab1 100644
--- a/src/sys.rs
+++ b/src/sys.rs
@@ -167,7 +167,7 @@ pub struct Token {
 /// source and delegate the implementations to it.
 pub struct Poll {
     /// The handle to wepoll/epoll/kqueue/... used to poll for events.
-    poller: Arc<Poller>,
+    pub(crate) poller: Arc<Poller>,
 
     /// The buffer of events returned by the poller.
     events: RefCell<Events>,