sys_util: implement FromRawFd for EventFd

This is used to make EventFd passed over unix domain socket, such as by
the plugin API.

TEST=./build_test
BUG=chromium:800626

Change-Id: Ifd6c81c51b31a376d57a007bf413a836f3af870a
Reviewed-on: https://chromium-review.googlesource.com/857906
Commit-Ready: Zach Reizner <zachr@chromium.org>
Tested-by: Zach Reizner <zachr@chromium.org>
Reviewed-by: Stephen Barber <smbarber@chromium.org>
Reviewed-by: Dylan Reid <dgreid@chromium.org>

1 files changed, 8 insertions, 0 deletions

diff --git a/sys_util/src/eventfd.rs b/sys_util/src/eventfd.rs
index 9298a05..ffdfadb 100644
--- a/sys_util/src/eventfd.rs
+++ b/sys_util/src/eventfd.rs
@@ -83,6 +83,14 @@ impl AsRawFd for EventFd {
     }
 }
 
+impl FromRawFd for EventFd {
+    unsafe fn from_raw_fd(fd: RawFd) -> Self {
+        EventFd {
+            eventfd: File::from_raw_fd(fd)
+        }
+    }
+}
+
 unsafe impl ::Pollable for EventFd {
     fn pollable_fd(&self) -> RawFd {
         self.eventfd.as_raw_fd()