Set NODELETE flag after checking for NULL pointer

The commit b632bdd3 moved the setting of the DF_1_NODELETE flag earlier
in the dl_open_worker function. However when calling dlopen with both
RTLD_NODELETE and RTLD_NOLOAD, the pointer returned by _dl_map_object is
NULL. This condition is checked just after setting the flag, while it
should be done before. Fix that.

Changelog:
	[BZ #19810]
	* elf/dl-open.c (dl_open_worker): Set DF_1_NODELETE flag later.
	* elf/tst-noload.c: New test case.
	* elf/Makefile (tests): Add tst-noload.

1 files changed, 73 insertions, 0 deletions

diff --git a/elf/tst-noload.c b/elf/tst-noload.c
new file mode 100644
index 0000000000..941450c10b
--- /dev/null
+++ b/elf/tst-noload.c
@@ -0,0 +1,73 @@
+/* Verify that RTLD_NOLOAD works as expected.
+
+   Copyright (C) 2016 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
+   <http://www.gnu.org/licenses/>.  */
+
+#include <dlfcn.h>
+#include <stdio.h>
+#include <gnu/lib-names.h>
+
+static int
+do_test (void)
+{
+  /* Test that no object is loaded with RTLD_NOLOAD.  */
+  void *h1 = dlopen (LIBM_SO, RTLD_LAZY | RTLD_NOLOAD);
+  if (h1 != NULL)
+    {
+      printf ("h1: DSO has been loaded while it should have not\n");
+      return 1;
+    }
+
+  /* This used to segfault in some glibc versions.  */
+  void *h2 = dlopen (LIBM_SO, RTLD_LAZY | RTLD_NOLOAD | RTLD_NODELETE);
+  if (h2 != NULL)
+    {
+      printf ("h2: DSO has been loaded while it should have not\n");
+      return 1;
+    }
+
+  /* Test that loading an already loaded object returns the same.  */
+  void *h3 = dlopen (LIBM_SO, RTLD_LAZY);
+  if (h3 == NULL)
+    {
+      printf ("h3: failed to open DSO: %s\n", dlerror ());
+      return 1;
+    }
+  void *h4 = dlopen (LIBM_SO, RTLD_LAZY | RTLD_NOLOAD);
+  if (h4 == NULL)
+    {
+      printf ("h4: failed to open DSO: %s\n", dlerror ());
+      return 1;
+    }
+  if (h4 != h3)
+    {
+      printf ("h4: should return the same object\n");
+      return 1;
+    }
+
+  /* Cleanup */
+  if (dlclose (h3) != 0)
+    {
+      printf ("h3: dlclose failed: %s\n", dlerror ());
+      return 1;
+    }
+
+  return 0;
+}
+
+#define TEST_FUNCTION do_test ()
+#include "../test-skeleton.c"