From 42e1c463fa93197a6d21f1630e6d675a429220c9 Mon Sep 17 00:00:00 2001
From: Christopher Kohlhoff <chris@kohlhoff.com>
Date: Wed, 9 Nov 2022 07:43:14 +1100
Subject: [PATCH] Fall back to fcntl if ioctl fails with ENOTTY when setting
 non-blocking mode.

---
 .../asio/detail/impl/descriptor_ops.ipp       | 37 +++++++++++++++++++
 1 file changed, 37 insertions(+)

diff --git a/asio/include/asio/detail/impl/descriptor_ops.ipp b/asio/include/asio/detail/impl/descriptor_ops.ipp
index 5ba6a18aa0..1a2578a758 100644
--- a/asio/include/asio/detail/impl/descriptor_ops.ipp
+++ b/asio/include/asio/detail/impl/descriptor_ops.ipp
@@ -69,7 +69,18 @@ int close(int d, state_type& state, asio::error_code& ec)
         ::fcntl(d, F_SETFL, flags & ~O_NONBLOCK);
 #else // defined(__SYMBIAN32__) || defined(__EMSCRIPTEN__)
       ioctl_arg_type arg = 0;
+# if defined(ENOTTY)
+      result = ::ioctl(d, FIONBIO, &arg);
+      get_last_error(ec, result < 0);
+      if (ec.value() == ENOTTY)
+      {
+        int flags = ::fcntl(d, F_GETFL, 0);
+        if (flags >= 0)
+          ::fcntl(d, F_SETFL, flags & ~O_NONBLOCK);
+      }
+# else // defined(ENOTTY)
       ::ioctl(d, FIONBIO, &arg);
+# endif // defined(ENOTTY)
 #endif // defined(__SYMBIAN32__) || defined(__EMSCRIPTEN__)
       state &= ~non_blocking;
 
@@ -103,6 +114,19 @@ bool set_user_non_blocking(int d, state_type& state,
   ioctl_arg_type arg = (value ? 1 : 0);
   int result = ::ioctl(d, FIONBIO, &arg);
   get_last_error(ec, result < 0);
+# if defined(ENOTTY)
+  if (ec.value() == ENOTTY)
+  {
+    int result = ::fcntl(d, F_GETFL, 0);
+    get_last_error(ec, result < 0);
+    if (result >= 0)
+    {
+      int flag = (value ? (result | O_NONBLOCK) : (result & ~O_NONBLOCK));
+      result = ::fcntl(d, F_SETFL, flag);
+      get_last_error(ec, result < 0);
+    }
+  }
+# endif // defined(ENOTTY)
 #endif // defined(__SYMBIAN32__) || defined(__EMSCRIPTEN__)
 
   if (result >= 0)
@@ -153,6 +177,19 @@ bool set_internal_non_blocking(int d, state_type& state,
   ioctl_arg_type arg = (value ? 1 : 0);
   int result = ::ioctl(d, FIONBIO, &arg);
   get_last_error(ec, result < 0);
+# if defined(ENOTTY)
+  if (ec.value() == ENOTTY)
+  {
+    int result = ::fcntl(d, F_GETFL, 0);
+    get_last_error(ec, result < 0);
+    if (result >= 0)
+    {
+      int flag = (value ? (result | O_NONBLOCK) : (result & ~O_NONBLOCK));
+      result = ::fcntl(d, F_SETFL, flag);
+      get_last_error(ec, result < 0);
+    }
+  }
+# endif // defined(ENOTTY)
 #endif // defined(__SYMBIAN32__) || defined(__EMSCRIPTEN__)
 
   if (result >= 0)