Add and use link-test-modules-rpath-link [BZ #28455]

DT_RUNPATH is only used to find the immediate dependencies of the
executable or shared object containing the DT_RUNPATH entry:

1. Define link-test-modules-rpath-link if $(build-hardcoded-path-in-tests)
is yes.
2. Use $(link-test-modules-rpath-link) in build-module-helper so that
test modules can dlopen modules with DT_RUNPATH.
3. Add a test to show why link-test-modules-rpath-link is needed.

This partially fixes BZ #28455.

1 files changed, 32 insertions, 0 deletions

diff --git a/elf/tst-global2.c b/elf/tst-global2.c
new file mode 100644
index 0000000000..9cbfae0961
--- /dev/null
+++ b/elf/tst-global2.c
@@ -0,0 +1,32 @@
+/* Test BZ #28455.
+   Copyright (C) 2022 Free Software Foundation, Inc.
+   This file is part of the GNU C Library.
+
+   The GNU C Library is free software; you can redistribute it and/or
+   modify it under the terms of the GNU Lesser General Public
+   License as published by the Free Software Foundation; either
+   version 2.1 of the License, or (at your option) any later version.
+
+   The GNU C Library is distributed in the hope that it will be useful,
+   but WITHOUT ANY WARRANTY; without even the implied warranty of
+   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+   Lesser General Public License for more details.
+
+   You should have received a copy of the GNU Lesser General Public
+   License along with the GNU C Library; if not, see
+   <https://www.gnu.org/licenses/>.  */
+
+/* In glibc configured with --enable-hardcoded-path-in-tests, a test
+   program built with -Wl,--enable-new-dtags, which adds DT_RUNPATH,
+   instead of DT_RPATH, can call a function in a shared library, which
+   dlopens another shared library.  */
+
+extern int test (void);
+
+static int
+do_test (void)
+{
+  return test ();
+}
+
+#include <support/test-driver.c>