On Wed, Jun 11, 2014 at 11:00:22AM +0200, Ján Tomko wrote:
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])
This is really re-inventing the gnulib compiler arg checking which I don't think is desirable.
@@ -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="$wantwarn -fstack-protector-all" + fi ;; *-*-freebsd*) dnl FreeBSD ships old gcc 4.2.1 which doesn't handle
I'd suggest we only list 'wantwarn="$wantwarn -fstack-protector-strong' here. Then, after the 'gl_WARN_ADD' call has processed everything in $wantwarn we check to see if $WARNING_CFLAGS contains the desired -fstack-protector-strong arg and if not, we call gl_WARN_ADD for -fstack-protector-all Regards, Daniel -- |: http://berrange.com -o- http://www.flickr.com/photos/dberrange/ :| |: http://libvirt.org -o- http://virt-manager.org :| |: http://autobuild.org -o- http://search.cpan.org/~danberr/ :| |: http://entangle-photo.org -o- http://live.gnome.org/gtk-vnc :|