configure: check compiler/linker support for RELRO and PIE options

Also, add AC_TRY_LDFLAGS m4 macro to help with checking ld flags.

WHATS_NEW

@@ -1,5 +1,6 @@
 Version 2.02.105 -
 =====================================
+  Automatically detect support for compiler/linker options to use RELRO and PIE.
   Add --splitsnapshot to lvconvert to separate out cow LV.
   Reinstate origin reload to complete lvconvert -s with active LVs. (2.02.98)
   Select only active volume groups if vgdisplay -A is used.

acinclude.m4

@@ -36,3 +36,24 @@ AC_DEFUN([AC_TRY_CCFLAG],
         ifelse([$4], [], [:], [$4])
     fi
 ])
+
+dnl AC_TRY_LDFLAGS([LDFLAGS], [VAR], [ACTION-IF-WORKS], [ACTION-IF-FAILS])
+dnl check if $CC supports given ld flags
+
+AC_DEFUN([AC_TRY_LDFLAGS],
+[
+    AC_REQUIRE([AC_PROG_CC])
+    ac_save_LDFLAGS=$LDFLAGS
+    LDFLAGS=$1
+	AC_CACHE_CHECK([whether $CC accepts $1 ld flags], [ac_cv_flag_$2],
+	[AC_LINK_IFELSE([AC_LANG_PROGRAM()],
+			[AS_VAR_SET([ac_cv_flag_$2], [yes])],
+			[AS_VAR_SET([ac_cv_flag_$2], [no])])])
+    LDLAGS=$ac_save_LDFLAGS
+    $2=AS_VAR_GET([ac_cv_flag_$2])
+    if test "$2" = yes; then
+        ifelse([$3], [], [:], [$3])
+    else
+        ifelse([$4], [], [:], [$4])
+    fi
+])

configure

@@ -740,6 +740,8 @@ PKG_CONFIG
 THIN_REPAIR_CMD
 THIN_DUMP_CMD
 THIN_CHECK_CMD
+HAVE_FULL_RELRO
+HAVE_PIE
 POW_LIB
 LIBOBJS
 ALLOCA
@@ -6741,6 +6743,85 @@ fi
 { $as_echo "$as_me:${as_lineno-$LINENO}: result: $STATIC_LINK" >&5
 $as_echo "$STATIC_LINK" >&6; }
 
+################################################################################
+
+
+    ac_save_CFLAGS=$CFLAGS
+    CFLAGS=-pie
+    { $as_echo "$as_me:${as_lineno-$LINENO}: checking whether $CC accepts -pie flag" >&5
+$as_echo_n "checking whether $CC accepts -pie flag... " >&6; }
+if test "${ac_cv_flag_HAVE_PIE+set}" = set; then :
+  $as_echo_n "(cached) " >&6
+else
+  cat confdefs.h - <<_ACEOF >conftest.$ac_ext
+/* end confdefs.h.  */
+
+int
+main ()
+{
+
+  ;
+  return 0;
+}
+_ACEOF
+if ac_fn_c_try_compile "$LINENO"; then :
+  ac_cv_flag_HAVE_PIE=yes
+else
+  ac_cv_flag_HAVE_PIE=no
+fi
+rm -f core conftest.err conftest.$ac_objext conftest.$ac_ext
+fi
+{ $as_echo "$as_me:${as_lineno-$LINENO}: result: $ac_cv_flag_HAVE_PIE" >&5
+$as_echo "$ac_cv_flag_HAVE_PIE" >&6; }
+    CFLAGS=$ac_save_CFLAGS
+    HAVE_PIE=$ac_cv_flag_HAVE_PIE
+    if test "HAVE_PIE" = yes; then
+        :
+    else
+        :
+    fi
+
+
+
+
+    ac_save_LDFLAGS=$LDFLAGS
+    LDFLAGS=-Wl,-z,relro,-z,now
+	{ $as_echo "$as_me:${as_lineno-$LINENO}: checking whether $CC accepts -Wl,-z,relro,-z,now ld flags" >&5
+$as_echo_n "checking whether $CC accepts -Wl,-z,relro,-z,now ld flags... " >&6; }
+if test "${ac_cv_flag_HAVE_FULL_RELRO+set}" = set; then :
+  $as_echo_n "(cached) " >&6
+else
+  cat confdefs.h - <<_ACEOF >conftest.$ac_ext
+/* end confdefs.h.  */
+
+int
+main ()
+{
+
+  ;
+  return 0;
+}
+_ACEOF
+if ac_fn_c_try_link "$LINENO"; then :
+  ac_cv_flag_HAVE_FULL_RELRO=yes
+else
+  ac_cv_flag_HAVE_FULL_RELRO=no
+fi
+rm -f core conftest.err conftest.$ac_objext \
+    conftest$ac_exeext conftest.$ac_ext
+fi
+{ $as_echo "$as_me:${as_lineno-$LINENO}: result: $ac_cv_flag_HAVE_FULL_RELRO" >&5
+$as_echo "$ac_cv_flag_HAVE_FULL_RELRO" >&6; }
+    LDLAGS=$ac_save_LDFLAGS
+    HAVE_FULL_RELRO=$ac_cv_flag_HAVE_FULL_RELRO
+    if test "HAVE_FULL_RELRO" = yes; then
+        :
+    else
+        :
+    fi
+
+
+
 ################################################################################
 
 

configure.in

@@ -158,6 +158,13 @@ AC_ARG_ENABLE(static_link,
 	      STATIC_LINK=$enableval, STATIC_LINK=no)
 AC_MSG_RESULT($STATIC_LINK)
 
+################################################################################
+dnl -- Check if compiler/linker supports PIE and RELRO
+AC_TRY_CCFLAG([-pie], [HAVE_PIE], [], [])
+AC_SUBST(HAVE_PIE)
+AC_TRY_LDFLAGS([-Wl,-z,relro,-z,now], [HAVE_FULL_RELRO], [], [])
+AC_SUBST(HAVE_FULL_RELRO)
+
 ################################################################################
 dnl -- Prefix is /usr by default, the exec_prefix default is setup later
 AC_PREFIX_DEFAULT(/usr)