From 902f09a4f8d1ef99c570455c8f56635499b45fda Mon Sep 17 00:00:00 2001
From: Joseph Hickey <joseph.p.hickey@nasa.gov>
Date: Fri, 30 Oct 2020 16:54:57 -0400
Subject: [PATCH] Fix #637, fix OS_ModuleUnload for static modules

Ensure that the handle is not NULL before invoking dlclose().
In particular the handle will be NULL for static modules.
---
 src/os/portable/os-impl-posix-dl-loader.c | 21 ++++++++++++---------
 src/os/rtems/src/os-impl-loader.c         | 21 ++++++++++++---------
 2 files changed, 24 insertions(+), 18 deletions(-)

diff --git a/src/os/portable/os-impl-posix-dl-loader.c b/src/os/portable/os-impl-posix-dl-loader.c
index 55aa9ac3c..ff8c3e513 100644
--- a/src/os/portable/os-impl-posix-dl-loader.c
+++ b/src/os/portable/os-impl-posix-dl-loader.c
@@ -90,20 +90,23 @@ int32 OS_ModuleLoad_Impl(uint32 module_id, const char *translated_path)
  *-----------------------------------------------------------------*/
 int32 OS_ModuleUnload_Impl(uint32 module_id)
 {
-    int32 status = OS_ERROR;
+    int32 status = OS_SUCCESS;
 
     /*
     ** Attempt to close/unload the module
     */
-    dlerror();
-    if (dlclose(OS_impl_module_table[module_id].dl_handle) == 0)
-    {
-        OS_impl_module_table[module_id].dl_handle = NULL;
-        status                                    = OS_SUCCESS;
-    }
-    else
+    if (OS_impl_module_table[module_id].dl_handle != NULL)
     {
-        OS_DEBUG("Error unloading shared library: %s\n", dlerror());
+        dlerror();
+        if (dlclose(OS_impl_module_table[module_id].dl_handle) == 0)
+        {
+            OS_impl_module_table[module_id].dl_handle = NULL;
+        }
+        else
+        {
+            OS_DEBUG("Error unloading shared library: %s\n", dlerror());
+            status = OS_ERROR;
+        }
     }
 
     return status;
diff --git a/src/os/rtems/src/os-impl-loader.c b/src/os/rtems/src/os-impl-loader.c
index 89fbbedce..2fd7412c6 100644
--- a/src/os/rtems/src/os-impl-loader.c
+++ b/src/os/rtems/src/os-impl-loader.c
@@ -179,20 +179,23 @@ int32 OS_ModuleLoad_Impl(uint32 module_id, const char *translated_path)
  *-----------------------------------------------------------------*/
 int32 OS_ModuleUnload_Impl(uint32 module_id)
 {
-    int32 status = OS_ERROR;
+    int32 status = OS_SUCCESS;
 
     /*
     ** Attempt to close/unload the module
     */
-    dlerror();
-    if (dlclose(OS_impl_module_table[module_id].dl_handle) == 0)
-    {
-        OS_impl_module_table[module_id].dl_handle = NULL;
-        status                                    = OS_SUCCESS;
-    }
-    else
+    if (OS_impl_module_table[module_id].dl_handle != NULL)
     {
-        OS_DEBUG("Error unloading shared library: %s\n", dlerror());
+        dlerror();
+        if (dlclose(OS_impl_module_table[module_id].dl_handle) == 0)
+        {
+            OS_impl_module_table[module_id].dl_handle = NULL;
+        }
+        else
+        {
+            OS_DEBUG("Error unloading shared library: %s\n", dlerror());
+            status = OS_ERROR;
+        }
     }
 
     return status;