Unusual -rpath linkage for libdw.so

[Frank Ch. Eigler <fche at redhat dot com>]

Hi -

I have a question regarding commit e219f1c1b2 (by roland, from pre-git days)
that changed the way libdw/libdw.so is linked:

@@ -94,7 +93,10 @@ libdw_so_SOURCES =
 libdw.so: $(srcdir)/libdw.map libdw_pic.a \
          ../libdwfl/libdwfl_pic.a ../libebl/libebl.a \
          ../libelf/libelf.so
+# The rpath is necessary for libebl because its $ORIGIN use will
+# not fly in a setuid executable that links in libdw.
        $(LINK) -shared -o $@ -Wl,--soname,$@.$(VERSION),-z,defs \
+               -Wl,--enable-new-dtags,-rpath,$(pkglibdir) \
                -Wl,--version-script,$<,--no-undefined \
                -Wl,--whole-archive $(filter-out $<,$^) -Wl,--no-whole-archive\
                -ldl

This construct conflicts with the bundled-elfutils mode of systemtap
linkage (also written by roland back in '08), where that $(pkglibdir)
is made to have build-tree paths rather than install-tree paths: (from
systemtap top-level configure.ac)

  # Our libdw.so's libebl will look in $ORIGIN/../lib/... but that
  # $ORIGIN is where libdw.so resides, which is not where there is a ../lib.
  # Note that $libdir might be using a quoted use of $exec_prefix or $prefix.
  # So we must make sure to pass those settings to elfutils configure.
  elfutils_rpath="-Wl,--enable-new-dtags,-rpath,${libdir}/${PACKAGE_NAME}"
  here=`pwd`
  (mkdir -p build-elfutils && cd build-elfutils &&
   bash ${elfutils_srcdir}/configure --enable-libebl-subdir=${PACKAGE_NAME} \
                                --includedir="${here}/include-elfutils" \
                                --libdir="${here}/lib-elfutils" \
                                --exec-prefix="$exec_prefix" \
                                --prefix="$prefix" \
                                CFLAGS="${CFLAGS/-Wall/} $gnu89_inline_flag" \
                                LDFLAGS="$LDFLAGS $elfutils_rpath" &&


This in turn propagates build-tree DT_R*PATH into the .so files.
There appear to be no tools able to remove those erroneous paths.

Is there still a need for the libdw custom rpath usage?  I don't know
of any setuid users of -ldw.


- FChE