Re: [libvirt] [PATCH 1/2] Simplify RELRO_LDFLAGS
On 08/20/2013 08:39 AM, Guido Günther wrote:
by adding it to AM_LDFLAGS instead of every linking rule and
by avoiding a forked grep.
---
Daniel kind of nacked the AM_LDFLAGS part already but I think it's a
reasonable cleanup. We should rather use AM_LDFLAGS everywhere which
(we currently don't and which would be another cleanup). Or are there
any reasons to not have a read only GOT?
Personally, I like the idea of using AM_LDFLAGS everywhere, but as
Daniel and I have opposing opinions, we'll need a third person to speak up.
+++ b/m4/virt-linker-relro.m4
@@ -22,10 +22,10 @@ AC_DEFUN([LIBVIRT_LINKER_RELRO],[
AC_MSG_CHECKING([for how to force completely read-only GOT table])
RELRO_LDFLAGS=
- `$LD --help 2>&1 | grep -- "-z relro" >/dev/null` && \
- RELRO_LDFLAGS="-Wl,-z -Wl,relro"
- `$LD --help 2>&1 | grep -- "-z now" >/dev/null` && \
- RELRO_LDFLAGS="$RELRO_LDFLAGS -Wl,-z -Wl,now"
+ case `$LD --help 2>&1` in
+ *"-z relro"*) RELRO_LDFLAGS="-Wl,-z -Wl,relro" ;&
';&' is a bashism; it is not portable to configure scripts
+ *"-z now"*) RELRO_LDFLAGS="$RELRO_LDFLAGS
-Wl,-z -Wl,now" ;;
+ esac
Instead, this needs to be:
ld_help=`$LD --help 2>&1`
case $ld_help in
*"-z relro"*) RELRO_LDFLAGS="-Wl,-z -Wl,relro" ;;
esac
case $ld_help in
*"-z now"*) RELRO_LDFLAGS="$RELRO_LDFLAGS -Wl,-z -Wl,now" ;;
esac
@@ -1812,7 +1814,6 @@ libvirt_la_LDFLAGS = \
-version-info $(LIBVIRT_VERSION_INFO) \
$(LIBVIRT_NODELETE) \
$(AM_LDFLAGS) \
- $(RELRO_LDFLAGS) \
$(CYGWIN_EXTRA_LDFLAGS) \
$(MINGW_EXTRA_LDFLAGS) \
$(NULL)
Hmm - maybe I see why Daniel expressed his opinion for not using
$(AM_LDFLAGS) - notice that libraries to NOT use $(PIE_LDFLAGS)...
@@ -1964,7 +1963,6 @@ virtlockd_CFLAGS = \
virtlockd_LDFLAGS = \
$(AM_LDFLAGS) \
$(PIE_LDFLAGS) \
- $(RELRO_LDFLAGS) \
$(CYGWIN_EXTRA_LDFLAGS) \
$(MINGW_EXTRA_LDFLAGS) \
$(NULL)
...but executables do. But even then, maybe we want:
LIBRARY_LDFLAGS = $(AM_LDFLAGS)
EXEC_LDFLAGS = $(AM_LDFLAGS) $(PIE_LDFLAGS)
then use the appropriate $({LIBRARY,EXEC}_LDFLAGS) in each place, rather
than having lots of duplicate $(PIE_LDFLAGS)?
--
Eric Blake eblake redhat com +1-919-301-3266
Libvirt virtualization library http://libvirt.org
Attachments:
- signature.asc (application/pgp-signature — 621 bytes)