Bug 11941: ld.so: Improper assert map->l_init_called in dlclose

There is at least one use case where during exit a library destructor
might call dlclose() on a valid handle and have it fail with an
assertion. We must allow this case, it is a valid handle, and dlclose()
should not fail with an assert. In the future we might be able to return
an error that the dlclose() could not be completed because the opened
library has already been unloaded and destructors have run as part of
exit processing.

For more details see:
https://www.sourceware.org/ml/libc-alpha/2016-12/msg00859.html

1 files changed, 90 insertions, 0 deletions

diff --git a/elf/tst-nodelete-dlclose-dso.c b/elf/tst-nodelete-dlclose-dso.c
new file mode 100644
index 0000000..dd930f9
--- /dev/null
+++ b/elf/tst-nodelete-dlclose-dso.c
@@ -0,0 +1,90 @@
+/* Bug 11941: Improper assert map->l_init_called in dlclose.
+   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/>.  */
+
+/* This is the primary DSO that is loaded by the appliation.  This DSO
+   then loads a plugin with RTLD_NODELETE.  This plugin depends on this
+   DSO.  This dependency chain means that at application shutdown the
+   plugin will be destructed first.  Thus by the time this DSO is
+   destructed we will be calling dlclose on an object that has already
+   been destructed.  It is allowed to call dlclose in this way and
+   should not assert.  */
+#include <stdio.h>
+#include <stdlib.h>
+#include <dlfcn.h>
+
+/* Plugin to load.  */
+static void *plugin_lib = NULL;
+/* Plugin function.  */
+static void (*plugin_func) (void);
+#define LIB_PLUGIN "tst-nodelete-dlclose-plugin.so"
+
+/* This function is never called but the plugin references it.
+   We do this to avoid any future --as-needed from removing the
+   plugin's DT_NEEDED on this DSO (required for the test).  */
+void
+primary_reference (void)
+{
+  printf ("INFO: Called primary_reference function.\n");
+}
+
+void
+primary (void)
+{
+  char *error;
+
+  plugin_lib = dlopen (LIB_PLUGIN, RTLD_NOW | RTLD_LOCAL | RTLD_NODELETE);
+  if (plugin_lib == NULL)
+    {
+      printf ("ERROR: Unable to load plugin library.\n");
+      exit (EXIT_FAILURE);
+    }
+  dlerror ();
+
+  plugin_func = (void (*) (void)) dlsym (plugin_lib, "plugin_func");
+  error = dlerror ();
+  if (error != NULL)
+    {
+      printf ("ERROR: Unable to find symbol with error \"%s\".",
+	      error);
+      exit (EXIT_FAILURE);
+    }
+
+  return;
+}
+
+__attribute__ ((destructor))
+static void
+primary_dtor (void)
+{
+  int ret;
+
+  printf ("INFO: Calling primary destructor.\n");
+
+  /* The destructor runs in the test driver also, which
+     hasn't called primary, in that case do nothing.  */
+  if (plugin_lib == NULL)
+    return;
+
+  ret = dlclose (plugin_lib);
+  if (ret != 0)
+    {
+      printf ("ERROR: Calling dlclose failed with \"%s\"\n",
+	      dlerror ());
+      exit (EXIT_FAILURE);
+    }
+}