[PATCH] Makeconfig: Move -Wl,-rpath-link options before library references

[Carlos O'Donell]

On 4/25/19 8:36 AM, Florian Weimer wrote:
> Previously, the -Wl,-rpath-link options came after the libraries
> injected using LDLIBS-* variables on the link editor command line for
> main programs.  As a result, it could happen that installed libraries
> that reference glibc libraries used the installed glibc from the system
> directories, instead of the glibc from the build tree.  This can lead to
> link failures if the wrong version of libpthread.so.0 is used, for
> instance, due to differences in the internal GLIBC_PRIVATE interfaces,
> as seen with memusagestat and -lgd after commit
> f9b645b4b0a10c43753296ce3fa40053fa44606a ("memusagestat: use local glibc
> when linking [BZ #18465]").

This is ugly, thanks for fixing this.

> The isolation is necessarily imperfect because these installed
> libraries are linked against the installed glibc in the system
> directories.  However, in most cases, the built glibc will be newer
> than the installed glibc, and this link is permitted because of the
> ABI backwards compatibility glibc provides.
> 
> (Note: This patch depends on "Makeconfig: Move $(CC) to +link command
> variables".)

Right, the previously cleanup makes it possible to put things cleanly
after $(CC) now.

> 
> 2019-04-25  Florian Weimer  <fweimer@redhat.com>
> 
> 	Makeconfig: Move -Wl,-rpath-link options before library references.
> 	* Makeconfig (+link-pie, +link): Add $(link-libc-rpath-link).
> 	(link-libc): Remove $(link-libc-rpath-link).

OK with two comment suggestions accepted.

Reviewed-by: Carlos O'Donell <carlos@redhat.com>

> diff --git a/Makeconfig b/Makeconfig
> index 92c9b59bb5..76a5d41242 100644
> --- a/Makeconfig
> +++ b/Makeconfig
> @@ -428,8 +428,8 @@ ifndef +link-pie
>   	     $(link-extra-libs)
>   +link-pie-after-libc = $(+postctorS) $(+postinit)
>   define +link-pie
> -$(CC) $(+link-pie-before-libc) $(rtld-LDFLAGS) $(link-extra-flags) \
> -  $(link-libc) $(+link-pie-after-libc)
> +$(CC) $(link-libc-rpath-link) $(+link-pie-before-libc) $(rtld-LDFLAGS) \
> +  $(link-extra-flags) $(link-libc) $(+link-pie-after-libc)

OK, add $(link-libc-rpath-link) after $(CC) but before others.

>   $(call after-link,$@)
>   endef
>   define +link-pie-tests
> @@ -490,8 +490,8 @@ else  # not build-pie-default
>   	      $(link-extra-libs)
>   +link-after-libc = $(+postctor) $(+postinit)
>   define +link
> -$(CC) $(+link-before-libc) $(rtld-LDFLAGS) $(link-extra-flags) $(link-libc) \
> -  $(+link-after-libc)
> +$(CC) $(link-libc-rpath-link) $(+link-before-libc) $(rtld-LDFLAGS) \
> +  $(link-extra-flags) $(link-libc) $(+link-after-libc)

OK, likewise.

>   $(call after-link,$@)
>   endef
>   define +link-tests
> @@ -552,6 +552,15 @@ ifeq (yes,$(build-shared))
>   link-libc-rpath = -Wl,-rpath=$(rpath-link)
>   link-libc-rpath-link = -Wl,-rpath-link=$(rpath-link)
>   
> +# For programs which are not tests, $(link-libc-rpath-link) is added
> +# directly in $(+link), $(+link-pie) above, so that -Wl,-rpath-link

Suggest:
# directly in $(+link) and $(+link-pie) (above), so that -Wl,-rpath-link

> +# comes before the expansion of LDLIBS-* and affects libraries added
> +# there.  For shared objects, -Wl,-rpath-link is added via
> +# $(build-shlib-helper) and $(build-module-helper) in Makerules (also
> +# before the expansion of LDLIBS-* variables).

OK.

> +
> +# Test use -Wl,-rpath instead of -Wl,-rpath-link for

s/Test/Tests/g

> +# build-hardcoded-path-in-tests.
>   ifeq (yes,$(build-hardcoded-path-in-tests))
>   link-libc-tests-rpath-link = $(link-libc-rpath)
>   else
> @@ -562,7 +571,7 @@ link-libc-before-gnulib = $(common-objpfx)libc.so$(libc.so-version) \
>   			  $(common-objpfx)$(patsubst %,$(libtype.oS),c) \
>   			  $(as-needed) $(elf-objpfx)ld.so \
>   			  $(no-as-needed)
> -link-libc = $(link-libc-rpath-link) $(link-libc-before-gnulib) $(gnulib)
> +link-libc = $(link-libc-before-gnulib) $(gnulib)

OK. Removes it from link-libc to be placed in the +link/+link-pie earlier.

>   
>   link-libc-tests-after-rpath-link = $(link-libc-before-gnulib) $(gnulib-tests)
>   link-libc-tests = $(link-libc-tests-rpath-link) \
> 


-- 
Cheers,
Carlos.