From 85f5849d0b7be6de4a3d6f82209fa29f1e0b7a9c Mon Sep 17 00:00:00 2001
From: John Maguire <contact@johnmaguire.me>
Date: Fri, 11 Nov 2022 09:18:43 -0700
Subject: [PATCH] Fix a hang when shutting down Android (#772)

---
 overlay/tun_android.go | 4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

diff --git a/overlay/tun_android.go b/overlay/tun_android.go
index 3bea907..321aec8 100644
--- a/overlay/tun_android.go
+++ b/overlay/tun_android.go
@@ -28,11 +28,13 @@ func newTunFromFd(l *logrus.Logger, deviceFd int, cidr *net.IPNet, _ int, routes
 		return nil, err
 	}
 
+	// XXX Android returns an fd in non-blocking mode which is necessary for shutdown to work properly.
+	// Be sure not to call file.Fd() as it will set the fd to blocking mode.
 	file := os.NewFile(uintptr(deviceFd), "/dev/net/tun")
 
 	return &tun{
 		ReadWriteCloser: file,
-		fd:              int(file.Fd()),
+		fd:              deviceFd,
 		cidr:            cidr,
 		l:               l,
 		routeTree:       routeTree,