Warn and return for duplicated plugin

If a plugin has been loaded already, we should warn and return, instead
of adding it on the plugin list.

	PR ld/20321
	* plugin.c (plugin_opt_plugin): Warn and return if plugin has
	been loaded already.
	* testsuite/ld-plugin/lto.exp: Run PR ld/20321 test.
	* testsuite/ld-plugin/pr20321.c: New file.

1 files changed, 13 insertions, 0 deletions

diff --git a/ld/plugin.c b/ld/plugin.c
index 4c161d1..924b59c 100644
--- a/ld/plugin.c
+++ b/ld/plugin.c
@@ -237,6 +237,7 @@ void
 plugin_opt_plugin (const char *plugin)
 {
   plugin_t *newplug;
+  plugin_t *curplug = plugins_list;
 
   newplug = xmalloc (sizeof *newplug);
   memset (newplug, 0, sizeof *newplug);
@@ -245,6 +246,18 @@ plugin_opt_plugin (const char *plugin)
   if (!newplug->dlhandle)
     einfo (_("%P%F: %s: error loading plugin: %s\n"), plugin, dlerror ());
 
+  /* Check if plugin has been loaded already.  */
+  while (curplug)
+    {
+      if (newplug->dlhandle == curplug->dlhandle)
+	{
+	  einfo (_("%P: %s: duplicated plugin\n"), plugin);
+	  free (newplug);
+	  return;
+	}
+      curplug = curplug->next;
+    }
+
   /* Chain on end, so when we run list it is in command-line order.  */
   *plugins_tail_chain_ptr = newplug;
   plugins_tail_chain_ptr = &newplug->next;