[v2,1/4] Makeconfig: Add libgcc directory to rtld-prefix search path

  * This needs to be done twice, for test runs with and without
  --enable-hardcoded-path-in-tests
* Also, we need to query the used $(CC) for the library location.

* The container tests run ldd and dump the list of needed libraries, then
  copy these into the container.
* Without this patch, ldd may not find libgcc_s.so, resulting in"not found"
  output and no copying of the library.
* With this patch, the library is picked up independent of its location (as
  long as the proper directory is provided) and copied into the testroot.

* This does not mean yet that ld.so in the testroot actually finds it.

Signed-off-by: Andreas K. Hüttel <dilfridge@gentoo.org>
---
 Makeconfig | 12 ++++++++++--
 1 file changed, 10 insertions(+), 2 deletions(-)
  

On 08/02/25 13:09, Andreas K. Hüttel wrote:
> * This needs to be done twice, for test runs with and without
>   --enable-hardcoded-path-in-tests
> * Also, we need to query the used $(CC) for the library location.
> 
> * The container tests run ldd and dump the list of needed libraries, then
>   copy these into the container.
> * Without this patch, ldd may not find libgcc_s.so, resulting in"not found"
>   output and no copying of the library.
> * With this patch, the library is picked up independent of its location (as
>   long as the proper directory is provided) and copied into the testroot.
> 
> * This does not mean yet that ld.so in the testroot actually finds it.
> 
> Signed-off-by: Andreas K. Hüttel <dilfridge@gentoo.org>
> ---
>  Makeconfig | 12 ++++++++++--
>  1 file changed, 10 insertions(+), 2 deletions(-)
> 
> diff --git a/Makeconfig b/Makeconfig
> index d0108d2caa..0820f860b2 100644
> --- a/Makeconfig
> +++ b/Makeconfig
> @@ -635,7 +635,7 @@ link-libc-printers-tests = $(link-libc-rpath) \
>  # This is how to find at build-time things that will be installed there.
>  rpath-dirs = math elf dlfcn nss nis rt resolv mathvec support
>  rpath-link = \
> -$(common-objdir):$(subst $(empty) ,:,$(patsubst ../$(subdir),.,$(rpath-dirs:%=$(common-objpfx)%)))
> +$(common-objdir):$(subst $(empty) ,:,$(patsubst ../$(subdir),.,$(rpath-dirs:%=$(common-objpfx)%))):$(gnulib-extralibdir)
>  else  # build-static
>  link-libc = $(common-objpfx)libc.a $(otherlibs) $(gnulib) $(common-objpfx)libc.a $(gnulib)
>  link-libc-tests = $(common-objpfx)libc.a $(otherlibs) $(gnulib-tests) $(common-objpfx)libc.a $(gnulib-tests)
> @@ -692,6 +692,11 @@ link-libc-static-tests = -Wl,--start-group $(common-objpfx)libc.a $(static-gnuli
>  # some cases and it is preferable to link with libgcc_eh or libgcc_s
>  # so that the testing is as similar as possible to how programs will
>  # be built with the installed glibc.
> +# This leads to moderate difficulties, also since distributions may
> +# install libgcc_s.so in directories only found via ld.so.conf, e.g.
> +# to be able to switch between gcc versions. We need to add the
> +# corresponding directory to the library search path to make sure
> +# our test programs can find it.
>  #
>  # Some architectures have architecture-specific systems for exception
>  # handling that may involve undefined references to
> @@ -709,6 +714,7 @@ libgcc_eh := -Wl,--as-needed -lgcc_s $(libunwind) -Wl,--no-as-needed
>  gnulib-arch =
>  gnulib = -lgcc $(gnulib-arch)
>  gnulib-tests := -lgcc $(libgcc_eh)
> +gnulib-extralibdir := $(shell dirname $$($(CC) -print-file-name=libgcc_s.so$(libgcc_s.so-version)))

This does not return a workable path on a Ubuntu installation, it seems
that the internal $(libgcc_s.so-version) is not evaluated correctly:

$ arm-linux-gnueabihf-gcc -print-file-name=libgcc_s.so.1
/usr/lib/gcc-cross/arm-linux-gnueabihf/13/../../../../arm-linux-gnueabihf/lib/libgcc_s.so.1

But I am seeing '/usr/lib/gcc-cross/arm-linux-gnueabihf/13' which is 
-print-file-name for 'libgcc_s.so.1'.

The:

  gnulib-extralibdir = $(shell $(CC) -print-file-name=libgcc_s.so$(libgcc_s.so-version) | sed 's#/[^/]*$$##')

evaluates to a correct path.  With this change I only see a failure,
and only without --enable-hardcoded-path-in-tests:

FAIL: elf/tst-pathopt

Because the test issues the loader through a shell script without
the $(gnulib-extralibdir).  The following change fixes it:

diff --git a/elf/Makefile b/elf/Makefile
index 1ea0e7037e..f0c4bed8ce 100644
--- a/elf/Makefile
+++ b/elf/Makefile
@@ -1869,7 +1869,7 @@ $(objpfx)lateglobal.out: $(objpfx)ltglobmod1.so $(objpfx)ltglobmod2.so
 $(objpfx)tst-pathopt.out: tst-pathopt.sh $(objpfx)tst-pathopt \
                          $(objpfx)pathoptobj.so
        $(SHELL) $< $(common-objpfx) '$(test-wrapper-env)' \
-                '$(run-program-env)'; \
+                '$(run-program-env)' '$(gnulib-extralibdir)'; \
        $(evaluate-test)

 $(objpfx)tst-rtld-load-self.out: tst-rtld-load-self.sh $(objpfx)ld.so
diff --git a/elf/tst-pathopt.sh b/elf/tst-pathopt.sh
index b1539c8ee9..e5b124ea65 100755
--- a/elf/tst-pathopt.sh
+++ b/elf/tst-pathopt.sh
@@ -22,6 +22,7 @@ set -e
 common_objpfx=$1
 test_wrapper_env=$2
 run_program_env=$3
+gnulib_extralibdir=$4

 test -e ${common_objpfx}elf/will-be-empty &&
   rm -fr ${common_objpfx}elf/will-be-empty
@@ -32,7 +33,7 @@ cp ${common_objpfx}elf/pathoptobj.so ${common_objpfx}elf/for-renamed/renamed.so

 ${test_wrapper_env} \
 ${run_program_env} \
-LD_LIBRARY_PATH=${common_objpfx}elf/will-be-empty:${common_objpfx}elf/for-renamed:${common_objpfx}.:${common_objpfx}dlfcn \
+LD_LIBRARY_PATH=${common_objpfx}elf/will-be-empty:${common_objpfx}elf/for-renamed:${common_objpfx}.:${common_objpfx}dlfcn:${gnulib_extralibdir} \
   ${common_objpfx}elf/ld.so ${common_objpfx}elf/tst-pathopt \
     > ${common_objpfx}elf/tst-pathopt.out


>  static-gnulib-arch =
>  # By default, elf/static-stubs.o, instead of -lgcc_eh, is used to
>  # statically link programs.  When --disable-shared is used, we use
> @@ -781,10 +787,12 @@ endif
>  
>  # How to run a program we just linked with our library.
>  # The program binary is assumed to be $(word 2,$^).
> +# We may require additional libraries from gcc (e.g. libgcc_s.so for exception
> +# handling), which unfortunately somewhat breaks the isolation.
>  built-program-file = $(dir $(word 2,$^))$(notdir $(word 2,$^))
>  rtld-prefix = $(elf-objpfx)$(rtld-installed-name)			      \
>  	      --library-path						      \
> -	      $(rpath-link)$(patsubst %,:%,$(sysdep-library-path))
> +	      $(rpath-link)$(patsubst %,:%,$(sysdep-library-path)):$(gnulib-extralibdir)
>  ifeq (yes,$(build-shared))
>  comma = ,
>  sysdep-library-path = \