From b9e66bfcfb572c11e8cfa54a9b9af76cad8d319a Mon Sep 17 00:00:00 2001
From: sg <goldsimon@gmx.de>
Date: Fri, 10 Feb 2017 21:18:08 +0100
Subject: [PATCH] Provide a better way to include system's <errno.h> for errno
 + error numbers (LWIP_ERRNO_INCLUDE can't be defined to <errno.h> at least on
 GCC/linux)

---
 src/include/lwip/arch.h  | 3 ++-
 src/include/lwip/errno.h | 7 ++++++-
 2 files changed, 8 insertions(+), 2 deletions(-)

diff --git a/src/include/lwip/arch.h b/src/include/lwip/arch.h
index fa627459..6097619a 100644
--- a/src/include/lwip/arch.h
+++ b/src/include/lwip/arch.h
@@ -296,7 +296,8 @@ extern "C" {
 #endif /* LWIP_UNUSED_ARG */
 
 /** LWIP_PROVIDE_ERRNO==1: Let lwIP provide ERRNO values and the 'errno' variable.
- * If this is disabled, cc.h must either define 'errno', include <errno.h> or
+ * If this is disabled, cc.h must either define 'errno', include <errno.h>,
+ * define LWIP_ERRNO_STDINCLUDE to get <errno.h> included or
  * define LWIP_ERRNO_INCLUDE to <errno.h> or equivalent.
  */
 #if defined __DOXYGEN__
diff --git a/src/include/lwip/errno.h b/src/include/lwip/errno.h
index 641cffb0..48d6b539 100644
--- a/src/include/lwip/errno.h
+++ b/src/include/lwip/errno.h
@@ -179,10 +179,15 @@ extern int errno;
 
 #else /* LWIP_PROVIDE_ERRNO */
 
-/* Define LWIP_ERRNO_INCLUDE to <errno.h> to include the error defines here */
+/* Define LWIP_ERRNO_STDINCLUDE if you want to include <errno.h> here */
+#ifdef LWIP_ERRNO_STDINCLUDE
+#include <errno.h>
+#else /* LWIP_ERRNO_STDINCLUDE */
+/* Define LWIP_ERRNO_INCLUDE to an equivalent of <errno.h> to include the error defines here */
 #ifdef LWIP_ERRNO_INCLUDE
 #include LWIP_ERRNO_INCLUDE
 #endif /* LWIP_ERRNO_INCLUDE */
+#endif /* LWIP_ERRNO_STDINCLUDE */
 
 #endif /* LWIP_PROVIDE_ERRNO */