From 1c707eda30a9b473db1b02e0aa58480a8d0ef1d0 Mon Sep 17 00:00:00 2001
From: He Sun <bochang.sh@antfin.com>
Date: Thu, 7 May 2020 11:30:55 +0800
Subject: [PATCH] Add support for monitoring epoll fds with epoll

---
 src/libos/src/net/io_multiplexing/epoll.rs | 10 ++++++++++
 1 file changed, 10 insertions(+)

diff --git a/src/libos/src/net/io_multiplexing/epoll.rs b/src/libos/src/net/io_multiplexing/epoll.rs
index b035bc9b..1041e771 100644
--- a/src/libos/src/net/io_multiplexing/epoll.rs
+++ b/src/libos/src/net/io_multiplexing/epoll.rs
@@ -97,6 +97,12 @@ impl EpollFile {
                 socket.fd()
             } else if let Ok(eventfd) = fd_ref.as_event() {
                 eventfd.get_host_fd()
+            } else if let Ok(epoll_file) = fd_ref.as_epfile() {
+                let target_host_fd = epoll_file.get_host_fd();
+                if self.host_fd == target_host_fd {
+                    return_errno!(EINVAL, "epfd should not be same as the target fd");
+                }
+                target_host_fd
             } else {
                 return_errno!(EPERM, "unsupported file type");
             }
@@ -145,6 +151,10 @@ impl EpollFile {
 
         Ok(ret)
     }
+
+    fn get_host_fd(&self) -> c_int {
+        self.host_fd
+    }
 }
 
 impl Drop for EpollFile {