From 3b935595859e0232b74594c5aca6da88a31f90b3 Mon Sep 17 00:00:00 2001
From: Florian Weimer <fweimer@redhat.com>
Date: Wed, 6 Feb 2019 16:26:39 +0100
Subject: support: Use dlerror to detect NULL symbols in xdlsym

---
 support/xdlfcn.c | 20 ++++++++++----------
 1 file changed, 10 insertions(+), 10 deletions(-)

(limited to 'support')

diff --git a/support/xdlfcn.c b/support/xdlfcn.c
index 2f2ac76003..b2e5c21134 100644
--- a/support/xdlfcn.c
+++ b/support/xdlfcn.c
@@ -28,22 +28,25 @@ xdlopen (const char *filename, int flags)
   if (dso == NULL)
     FAIL_EXIT1 ("error: dlopen: %s\n", dlerror ());
 
-  /* Clear any errors.  */
-  dlerror ();
-
   return dso;
 }
 
 void *
 xdlsym (void *handle, const char *symbol)
 {
+  /* Clear any pending errors.  */
+  dlerror ();
+
   void *sym = dlsym (handle, symbol);
 
   if (sym == NULL)
-    FAIL_EXIT1 ("error: dlsym: %s\n", dlerror ());
-
-  /* Clear any errors.  */
-  dlerror ();
+    {
+      const char *error = dlerror ();
+      if (error != NULL)
+        FAIL_EXIT1 ("error: dlsym: %s\n", error);
+      /* If there was no error, we found a NULL symbol.  Return the
+         NULL value in this case.  */
+    }
 
   return sym;
 }
@@ -53,7 +56,4 @@ xdlclose (void *handle)
 {
   if (dlclose (handle) != 0)
     FAIL_EXIT1 ("error: dlclose: %s\n", dlerror ());
-
-  /* Clear any errors.  */
-  dlerror ();
 }
-- 
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