ref: 610c14ce80ad1a6754a9e2743e6799cf45a093c5
parent: cea38f1c8c8ff58efa328e4ef5b26818d1b9e707
author: Jean-Marc Valin <jmvalin@jmvalin.ca>
date: Thu Feb 22 12:18:57 EST 2018
Adding -D_FORTIFY_SOURCE=2 when possible
--- a/configure.ac
+++ b/configure.ac
@@ -853,6 +853,10 @@
])
])
+AS_IF([test x$ac_cv_c_compiler_gnu = xyes],
+ [AX_ADD_FORTIFY_SOURCE]
+)
+
CFLAGS="$CFLAGS -W"
warn_CFLAGS="-Wall -Wextra -Wcast-align -Wnested-externs -Wshadow -Wstrict-prototypes"
--- /dev/null
+++ b/m4/ax_add_fortify_source.m4
@@ -1,0 +1,53 @@
+# ===========================================================================
+# Modified from https://www.gnu.org/software/autoconf-archive/ax_add_fortify_source.html
+# ===========================================================================
+#
+# SYNOPSIS
+#
+# AX_ADD_FORTIFY_SOURCE
+#
+# DESCRIPTION
+#
+# Check whether -D_FORTIFY_SOURCE=2 can be added to CFLAGS without macro
+# redefinition warnings. Some distributions (such as Gentoo Linux) enable
+# _FORTIFY_SOURCE globally in their compilers, leading to unnecessary
+# warnings in the form of
+#
+# <command-line>:0:0: error: "_FORTIFY_SOURCE" redefined [-Werror]
+# <built-in>: note: this is the location of the previous definition
+#
+# which is a problem if -Werror is enabled. This macro checks whether
+# _FORTIFY_SOURCE is already defined, and if not, adds -D_FORTIFY_SOURCE=2
+# to CFLAGS.
+#
+# LICENSE
+#
+# Copyright (c) 2017 David Seifert <soap@gentoo.org>
+#
+# Copying and distribution of this file, with or without modification, are
+# permitted in any medium without royalty provided the copyright notice
+# and this notice are preserved. This file is offered as-is, without any
+# warranty.
+
+#serial 1
+
+AC_DEFUN([AX_ADD_FORTIFY_SOURCE],[
+ AC_MSG_CHECKING([whether to add -D_FORTIFY_SOURCE=2 to CFLAGS])
+ AC_LINK_IFELSE([
+ AC_LANG_SOURCE(
+ [[
+ int main() {+ #ifndef _FORTIFY_SOURCE
+ return 0;
+ #else
+ this_is_an_error;
+ #endif
+ }
+ ]]
+ )], [
+ AC_MSG_RESULT([yes])
+ CFLAGS="$CFLAGS -D_FORTIFY_SOURCE=2"
+ ], [
+ AC_MSG_RESULT([no])
+ ])
+])