Use epoll_create() instead of epoll_create1()

src/sys/unix/selector/epoll.rs

@@ -23,21 +23,18 @@ pub struct Selector {
 
 impl Selector {
     pub fn new() -> io::Result<Selector> {
-        // According to libuv, `EPOLL_CLOEXEC` is not defined on Android API <
-        // 21. But `EPOLL_CLOEXEC` is an alias for `O_CLOEXEC` on that platform,
-        // so we use it instead.
-        #[cfg(target_os = "android")]
-        let flag = libc::O_CLOEXEC;
-        #[cfg(not(target_os = "android"))]
-        let flag = libc::EPOLL_CLOEXEC;
-
-        syscall!(epoll_create1(flag)).map(|ep| Selector {
-            #[cfg(debug_assertions)]
-            id: NEXT_ID.fetch_add(1, Ordering::Relaxed),
-            ep,
-            #[cfg(debug_assertions)]
-            has_waker: AtomicBool::new(false),
-        })
+        // Using epoll_create() followed by fcntl() instead of epoll_create1() with EPOLL_CLOEXEC
+        // flag for backwards compatibility. Android API < 21 does not have EPOLL_CLOEXEC constant
+        // defined and Android API 16 does not have epoll_create1() at all.
+        syscall!(epoll_create(1))
+            .and_then(|ep| syscall!(fcntl(ep, libc::F_SETFD, libc::FD_CLOEXEC)).map(|_| ep))
+            .map(|ep| Selector {
+                #[cfg(debug_assertions)]
+                id: NEXT_ID.fetch_add(1, Ordering::Relaxed),
+                ep,
+                #[cfg(debug_assertions)]
+                has_waker: AtomicBool::new(false),
+            })
     }
 
     pub fn try_clone(&self) -> io::Result<Selector> {