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
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