From feb267e61184887bb0cd1da09e62762ef0bbe9a4 Mon Sep 17 00:00:00 2001
From: Ben Noordhuis <info@bnoordhuis.nl>
Date: Sun, 18 Dec 2011 16:49:37 +0100
Subject: [PATCH] unix: it's legal for dlsym() to return NULL

A symbol name can map to NULL. Check dlerror() to see if a real error happened.
---
 include/uv.h  |  3 ++-
 src/unix/dl.c | 10 ++++++++--
 2 files changed, 10 insertions(+), 3 deletions(-)

diff --git a/include/uv.h b/include/uv.h
index e8b70b18..a2007087 100644
--- a/include/uv.h
+++ b/include/uv.h
@@ -1250,7 +1250,8 @@ UV_EXTERN uv_err_t uv_dlopen(const char* filename, uv_lib_t* library);
 UV_EXTERN uv_err_t uv_dlclose(uv_lib_t library);
 
 /*
- * Retrieves a data pointer from a dynamic library.
+ * Retrieves a data pointer from a dynamic library. It is legal for a symbol to
+ * map to NULL.
  */
 UV_EXTERN uv_err_t uv_dlsym(uv_lib_t library, const char* name, void** ptr);
 
diff --git a/src/unix/dl.c b/src/unix/dl.c
index 01f51d3e..41c244d7 100644
--- a/src/unix/dl.c
+++ b/src/unix/dl.c
@@ -53,8 +53,14 @@ uv_err_t uv_dlclose(uv_lib_t library) {
 
 
 uv_err_t uv_dlsym(uv_lib_t library, const char* name, void** ptr) {
-  void* address = dlsym(library, name);
-  if (address == NULL) {
+  void* address;
+
+  /* Reset error status. */
+  dlerror();
+
+  address = dlsym(library, name);
+
+  if (dlerror()) {
     return uv_inval_;
   }