From: Steffan Karger <steffan@karger.me>
Date: Sun, 13 Nov 2016 18:03:23 +0000 (+0100)
Subject: Fix builds on compilers without anonymous union support
X-Git-Tag: v2.4_beta1~26
X-Git-Url: http://git.ipfire.org/?a=commitdiff_plain;h=9223336a88bc065348d0ce37621bbf2b1087ba0e;p=thirdparty%2Fopenvpn.git

Fix builds on compilers without anonymous union support

The "Don't dereference type-punned pointers" patch introduced an anonymous
union, which older compilers do not support (or refuse to support when
-std=c99 is defined).  Add a configure check, and some wrapper defines to
repair builds on those compilers.

Signed-off-by: Steffan Karger <steffan@karger.me>
Acked-by: Gert Doering <gert@greenie.muc.de>
Message-Id: <1479060203-4472-1-git-send-email-steffan@karger.me>
URL: http://www.mail-archive.com/search?l=mid&q=1479060203-4472-1-git-send-email-steffan@karger.me
Signed-off-by: Gert Doering <gert@greenie.muc.de>
---

diff --git a/configure.ac b/configure.ac
index e44f61933..18c772d62 100644
--- a/configure.ac
+++ b/configure.ac
@@ -390,6 +390,12 @@ AC_DEFINE_UNQUOTED([IPROUTE_PATH], ["$IPROUTE"], [Path to iproute tool])
 AC_DEFINE_UNQUOTED([ROUTE_PATH], ["$ROUTE"], [Path to route tool])
 AC_DEFINE_UNQUOTED([SYSTEMD_ASK_PASSWORD_PATH], ["$SYSTEMD_ASK_PASSWORD"], [Path to systemd-ask-password tool])
 
+# Set -std=c99 unless user already specified a -std=
+case "${CFLAGS}" in
+  *-std=*) ;;
+  *)       CFLAGS="${CFLAGS} -std=c99" ;;
+esac
+
 #
 # Libtool
 #
@@ -553,6 +559,28 @@ AC_CHECK_DECLS(
 	,
 	[[${SOCKET_INCLUDES}]]
 )
+AC_CHECKING([anonymous union support])
+AC_COMPILE_IFELSE(
+	[AC_LANG_PROGRAM(
+		[[
+			struct mystruct {
+			  union {
+			    int m1;
+			    char m2;
+			  };
+			};
+		]],
+		[[
+			struct mystruct s;
+			s.m1 = 1; s.m2 = 2;
+		]]
+	)],
+	[
+		AC_MSG_RESULT([yes])
+		AC_DEFINE([HAVE_ANONYMOUS_UNION_SUPPORT], [], [Compiler supports anonymous unions])
+	],
+	[AC_MSG_RESULT([no])]
+)
 
 dnl We emulate signals in Windows
 AC_CHECK_DECLS(
@@ -1148,12 +1176,6 @@ if test "${enable_pkcs11}" = "yes"; then
 	)
 fi
 
-# Set -std=c99 unless user already specified a -std=
-case "${CFLAGS}" in
-  *-std=*) ;;
-  *)       CFLAGS="${CFLAGS} -std=c99" ;;
-esac
-
 if test "${enable_pedantic}" = "yes"; then
 	enable_strict="yes"
 	CFLAGS="${CFLAGS} -pedantic"
diff --git a/src/openvpn/mroute.h b/src/openvpn/mroute.h
index 5fe17e7f3..8f7a06423 100644
--- a/src/openvpn/mroute.h
+++ b/src/openvpn/mroute.h
@@ -96,7 +96,17 @@ struct mroute_addr {
       uint8_t prefix[12];
       in_addr_t addr;		/* _network order_ IPv4 address */
     } v4mappedv6;
-  };
+  }
+#ifndef HAVE_ANONYMOUS_UNION_SUPPORT
+/* Wrappers to support compilers that do not grok anonymous unions */
+  mroute_union
+#define raw_addr mroute_union.raw_addr
+#define eth_addr mroute_union.eth_addr
+#define v4 mroute_union.v4
+#define v6 mroute_union.v6
+#define v4mappedv6 mroute_union.v4mappedv6
+#endif
+  ;
 };
 
 /* Double-check that struct packing works as expected */