Add missing stdio.h include for the _FORTIFY_SOURCE=2 check.

Implementations of _FORTIFY_SOURCE require the header file to be
included.  Also remove the useless test of an empty program with
_FORTIFY_SOURCE defined.  Pointed out by Florian Weimer.

2 files changed, 4 insertions, 31 deletions

diff --git a/configure b/configure
index b5d57d6dc..2a8b219b4 100755
--- a/configure
+++ b/configure
@@ -34207,33 +34207,11 @@ else case e in #(
   e) cat confdefs.h - <<_ACEOF >conftest.$ac_ext
 /* end confdefs.h.  */
 
-
-int
-main (void)
-{
-char buf[4]; (void)sprintf(buf, "%s", "foo");
-
-  ;
-  return 0;
-}
-_ACEOF
-if ac_fn_c_try_link "$LINENO"
-then :
-  sudo_cv_use_fortify_source=yes
-else case e in #(
-  e) sudo_cv_use_fortify_source=no
-		 ;;
-esac
-fi
-rm -f core conftest.err conftest.$ac_objext conftest.beam \
-    conftest$ac_exeext conftest.$ac_ext
-
-	    cat confdefs.h - <<_ACEOF >conftest.$ac_ext
-/* end confdefs.h.  */
-
+		    #include <stdio.h>
 int
 main (void)
 {
+char buf[4]; sprintf(buf, "%s", "foo"); return buf[0];
 
   ;
   return 0;
diff --git a/m4/hardening.m4 b/m4/hardening.m4
index f7d2a8c29..45c501ff7 100644
--- a/m4/hardening.m4
+++ b/m4/hardening.m4
@@ -10,18 +10,13 @@ AC_DEFUN([SUDO_CHECK_HARDENING], [
 	    [sudo_cv_use_fortify_source],
 	    [AC_LINK_IFELSE([
 		    AC_LANG_PROGRAM(
-			[[]], [[char buf[4]; (void)sprintf(buf, "%s", "foo");]]
+			[[#include <stdio.h>]],
+			[[char buf[4]; sprintf(buf, "%s", "foo"); return buf[0];]]
 		    )],
 		    [sudo_cv_use_fortify_source=yes],
 		    [sudo_cv_use_fortify_source=no]
 		)
 	    ]
-	    [AC_LINK_IFELSE(
-		[AC_LANG_PROGRAM([[]], [[]])],
-		    [sudo_cv_use_fortify_source=yes],
-		    [sudo_cv_use_fortify_source=no]
-		)
-	    ]
 	)
 	if test "$sudo_cv_use_fortify_source" != yes; then
 	    CPPFLAGS="$O_CPPFLAGS"