From e09ce09c35ad0842cf237816a38665788eb7cdd0 Mon Sep 17 00:00:00 2001
From: Bruce Mitchener <bruce.mitchener@gmail.com>
Date: Thu, 31 Dec 2020 11:06:21 +0700
Subject: [PATCH] Cygwin doesn't have O_ASYNC, so fix compilation.

It looks like Cygwin doesn't actually support signal-based I/O,
so while this compiles, it won't be correct and will need
addressing in another way.
---
 src/inet.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/src/inet.c b/src/inet.c
index 8d990ad7..40b3c2c3 100644
--- a/src/inet.c
+++ b/src/inet.c
@@ -28,8 +28,8 @@
 #include <unistd.h>
 #endif /* DOS */
 
-#ifdef OS5
-/* Solaris doesn't define O_ASYNC, yet still defines FASYNC. */
+#if (defined(OS5) || defined(__CYGWIN__)) && !defined(O_ASYNC)
+/* Cygwin and Solaris don't define O_ASYNC, yet still define FASYNC. */
 #define O_ASYNC FASYNC
 #endif