Enable FORTIFY_SOURCE=3 when supported by the compiler

Barely tested, we should at least measure the performance impact and
ponder making that optional.

diff --git a/m4/pdns_d_fortify_source.m4 b/m4/pdns_d_fortify_source.m4
index 68e9be5ef5066aca18aba03a3d245e35ecf7b308..4a3322519fdd57d94e89511fc40e6791badfffad 100644 (file)
--- a/m4/pdns_d_fortify_source.m4
+++ b/m4/pdns_d_fortify_source.m4
@@ -21,8 +21,14 @@ dnl
 AC_DEFUN([AC_CC_D_FORTIFY_SOURCE],[
       OLD_CXXFLAGS="$CXXFLAGS"
       CXXFLAGS="-Wall -W -Werror $CXXFLAGS"
-      gl_COMPILER_OPTION_IF([-D_FORTIFY_SOURCE=2], [
-        CFLAGS="-U_FORTIFY_SOURCE -D_FORTIFY_SOURCE=2 $CFLAGS"
-        CXXFLAGS="-U_FORTIFY_SOURCE -D_FORTIFY_SOURCE=2 $OLD_CXXFLAGS"
-      ], [CXXFLAGS="$OLD_CXXFLAGS"], [AC_LANG_PROGRAM([[#include <stdio.h>]],[])])
-]) 
+      gl_COMPILER_OPTION_IF([-D_FORTIFY_SOURCE=3], [
+        CFLAGS="-U_FORTIFY_SOURCE -D_FORTIFY_SOURCE=3 $CFLAGS"
+        CXXFLAGS="-U_FORTIFY_SOURCE -D_FORTIFY_SOURCE=3 $OLD_CXXFLAGS"
+      ], [
+          gl_COMPILER_OPTION_IF([-D_FORTIFY_SOURCE=2], [
+            CFLAGS="-U_FORTIFY_SOURCE -D_FORTIFY_SOURCE=2 $CFLAGS"
+            CXXFLAGS="-U_FORTIFY_SOURCE -D_FORTIFY_SOURCE=2 $OLD_CXXFLAGS"
+          ], [CXXFLAGS="$OLD_CXXFLAGS"], [AC_LANG_PROGRAM([[#include <stdio.h>]],[])])
+         ]
+      , [AC_LANG_PROGRAM([[#include <stdio.h>]],[])])
+])