[libvirt] [PATCH 3/3] build: prefer -fstack-protector-strong to -all

Check upfront if it's supported, to avoid putting both of them on the command line. --- m4/virt-compile-warnings.m4 | 22 ++++++++++++++++++---- 1 file changed, 18 insertions(+), 4 deletions(-) diff --git a/m4/virt-compile-warnings.m4 b/m4/virt-compile-warnings.m4 index 196afa7..6d632f9 100644 --- a/m4/virt-compile-warnings.m4 +++ b/m4/virt-compile-warnings.m4 @@ -156,6 +156,15 @@ AC_DEFUN([LIBVIRT_COMPILE_WARNINGS],[ wantwarn="$wantwarn -Wframe-larger-than=4096" dnl wantwarn="$wantwarn -Wframe-larger-than=256" + AC_CACHE_CHECK([whether the C compiler supports stack-protector-strong], + [lv_cv_gcc_fstack_protector_strong], [ + save_CFLAGS=$CFLAGS + CFLAGS='-fstack-protector-strong -Werror' + AC_COMPILE_IFELSE([AC_LANG_PROGRAM([[]])], + [lv_cv_gcc_fstack_protector_strong=yes], + [lv_cv_gcc_fstack_protector_strong=no]) + CFLAGS=$save_CFLAGS]) + # Extra special flags dnl -fstack-protector stuff passes gl_WARN_ADD with gcc dnl on Mingw32, but fails when actually used @@ -164,13 +173,18 @@ AC_DEFUN([LIBVIRT_COMPILE_WARNINGS],[ dnl "error: -fstack-protector not supported for this target [-Werror]" ;; *-*-linux*) - dnl Fedora only uses -fstack-protector, but doesn't seem to - dnl be great overhead in adding -fstack-protector-all instead + dnl Prefer -fstack-protector-strong if it's available. + dnl There doesn't seem to be great overhead in adding + dnl -fstack-protector-all instead of -fstack-protector. dnl - dnl We also don't need ssp-buffer-size with -all, + dnl We also don't need ssp-buffer-size with -all or -strong, dnl since functions are protected regardless of buffer size. dnl wantwarn="$wantwarn --param=ssp-buffer-size=4" - wantwarn="$wantwarn -fstack-protector-all" + if test "$lv_cv_gcc_fstack_protector_strong" = yes; then + wantwarn="$wantwarn -fstack-protector-strong" + else + wantwarn="$wantwarn -fstack-protector-all" + fi ;; *-*-freebsd*) dnl FreeBSD ships old gcc 4.2.1 which doesn't handle -- 1.8.5.5