elf: Use _dl_catch_error from base namespace in dl-libc.c [BZ #27646]

dlerrror_run in elf/dl-libc.c needs to call GLRO (dl_catch_error)
from the base namespace, just like the exported dlerror
implementation.

Fixes commit b2964eb1d9 ("dlfcn:
Failures after dlmopen should not terminate process [BZ #24772]").

Reviewed-by: Siddhesh Poyarekar <siddhesh@sourceware.org>

elf/Makefile

@@ -223,7 +223,7 @@ tests += restest1 preloadtest loadfail multiload origtest resolvfail \
 	 tst-single_threaded tst-single_threaded-pthread \
 	 tst-tls-ie tst-tls-ie-dlmopen argv0test \
 	 tst-glibc-hwcaps tst-glibc-hwcaps-prepend tst-glibc-hwcaps-mask \
-	 tst-tls20 tst-tls21 tst-dlmopen-dlerror
+	 tst-tls20 tst-tls21 tst-dlmopen-dlerror tst-dlmopen-gethostbyname
 #	 reldep9
 tests-internal += loadtest unload unload2 circleload1 \
 	 neededtest neededtest2 neededtest3 neededtest4 \
@@ -347,6 +347,7 @@ modules-names = testobj1 testobj2 testobj3 testobj4 testobj5 testobj6 \
 		libmarkermod4-1 libmarkermod4-2 libmarkermod4-3 libmarkermod4-4 \
 		tst-tls20mod-bad tst-tls21mod tst-dlmopen-dlerror-mod \
 		tst-auxvalmod \
+		tst-dlmopen-gethostbyname-mod \
 
 # Most modules build with _ISOMAC defined, but those filtered out
 # depend on internal headers.
@@ -1832,3 +1833,5 @@ $(objpfx)tst-tls21mod.so: $(tst-tls-many-dynamic-modules:%=$(objpfx)%.so)
 
 $(objpfx)tst-getauxval-static.out: $(objpfx)tst-auxvalmod.so
 tst-getauxval-static-ENV = LD_LIBRARY_PATH=$(objpfx):$(common-objpfx)
+
+$(objpfx)tst-dlmopen-gethostbyname.out: $(objpfx)tst-dlmopen-gethostbyname-mod.so

elf/dl-libc.c

@@ -43,7 +43,7 @@ dlerror_run (void (*operate) (void *), void *args)
   const char *last_errstring = NULL;
   bool malloced;
 
-  int result = (_dl_catch_error (&objname, &last_errstring, &malloced,
+  int result = (GLRO (dl_catch_error) (&objname, &last_errstring, &malloced,
 				       operate, args)
 		?: last_errstring != NULL);
 

elf/tst-dlmopen-gethostbyname-mod.c

@@ -0,0 +1,29 @@
+/* Exercise dlerror_run in elf/dl-libc.c after dlmopen, via NSS.  Helper module.
+   Copyright (C) 2021 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/>.  */
+
+#include <netdb.h>
+#include <nss.h>
+
+void
+call_gethostbyname (void)
+{
+  __nss_configure_lookup ("hosts", "files");
+  /* This should not terminate the process due to a missing
+     _nss_files_getcanonname_r symbol.  */
+  gethostbyname ("localhost");
+}

elf/tst-dlmopen-gethostbyname.c

@@ -0,0 +1,31 @@
+/* Exercise dlerror_run in elf/dl-libc.c after dlmopen, via NSS (bug 27646).
+   Copyright (C) 2021 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/>.  */
+
+#include <support/xdlfcn.h>
+
+static int
+do_test (void)
+{
+  void *handle = xdlmopen (LM_ID_NEWLM, "tst-dlmopen-gethostbyname-mod.so",
+                           RTLD_NOW);
+  void (*call_gethostbyname) (void) = xdlsym (handle, "call_gethostbyname");
+  call_gethostbyname ();
+  return 0;
+}
+
+#include <support/test-driver.c>