# =========================================================================== # 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 CPPFLAGS without macro # redefinition warnings, other cpp warnings or linker. Some distributions # (such as Gentoo Linux) enable _FORTIFY_SOURCE globally in their # compilers, leading to unnecessary warnings in the form of # # :0:0: error: "_FORTIFY_SOURCE" redefined [-Werror] # : 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 CPPFLAGS. # # Newer mingw-w64 msys2 package comes with a bug in # headers-git-7.0.0.5546.d200317d-1. It broke -D_FORTIFY_SOURCE support, # and would need -lssp or -fstack-protector. See # https://github.com/msys2/MINGW-packages/issues/5803. Try to actually # link it. # # LICENSE # # Copyright (c) 2017 David Seifert # Copyright (c) 2019 Reini Urban # # 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 4 AC_DEFUN([AX_ADD_FORTIFY_SOURCE],[ ac_save_cflags=$CFLAGS ac_cwerror_flag=yes AX_CHECK_COMPILE_FLAG([-Werror],[CFLAGS="$CFLAGS -Werror"]) AC_MSG_CHECKING([whether to add -D_FORTIFY_SOURCE=2 to CPPFLAGS]) AC_LINK_IFELSE([ AC_LANG_PROGRAM([], [[ #ifndef _FORTIFY_SOURCE return 0; #else this_is_an_error; #endif ]] )], AC_LINK_IFELSE([ AC_LANG_SOURCE([[ #define _FORTIFY_SOURCE 2 #include int main() { char *s = " "; strcpy(s, "x"); return strlen(s)-1; } ]] )], [ AC_MSG_RESULT([yes]) CFLAGS=$ac_save_cflags CPPFLAGS="$CPPFLAGS -D_FORTIFY_SOURCE=2" ], [ AC_MSG_RESULT([no]) CFLAGS=$ac_save_cflags ], ), [ AC_MSG_RESULT([no]) CFLAGS=$ac_save_cflags ]) ])