Implement GET_MODULE_HANDLE_EX_FLAG_PIN for windows

Rather than leaking a reference, just call GetModuleHandleEx and pin the
module on Windows.
Reviewed-by: NTim Hudson <tjh@openssl.org>

crypto/init.c

@@ -82,6 +82,19 @@ DEFINE_RUN_ONCE_STATIC(ossl_init_base)
     base_inited = 1;
 
 #ifndef OPENSSL_USE_NODELETE
+# ifdef DSO_WIN32
+    {
+        HMODULE handle = NULL;
+        BOOL ret;
+
+        /* We don't use the DSO route for WIN32 because there is a better way */
+        ret = GetModuleHandleEx(GET_MODULE_HANDLE_EX_FLAG_FROM_ADDRESS
+                                | GET_MODULE_HANDLE_EX_FLAG_PIN,
+                                (void *)&base_inited, &handle);
+
+        return (ret == TRUE) ? 1 : 0;
+    }
+# else
     /*
      * Deliberately leak a reference to ourselves. This will force the library
      * to remain loaded until the atexit() handler is run a process exit.
@@ -92,6 +105,7 @@ DEFINE_RUN_ONCE_STATIC(ossl_init_base)
         dso = DSO_dsobyaddr(&base_inited, DSO_FLAG_NO_UNLOAD_ON_FREE);
         DSO_free(dso);
     }
+# endif
 #endif
 
     return 1;
@@ -591,22 +605,43 @@ int OPENSSL_atexit(void (*handler)(void))
     OPENSSL_INIT_STOP *newhand;
 
 #ifndef OPENSSL_USE_NODELETE
-    /*
-     * Deliberately leak a reference to the handler. This will force the
-     * library/code containing the handler to remain loaded until we run the
-     * atexit handler. If -znodelete has been used then this is unneccessary.
-     */
     {
-        DSO *dso = NULL;
         union {
             void *sym;
             void (*func)(void);
         } handlersym;
 
         handlersym.func = handler;
+# ifdef DSO_WIN32
+        {
+            HMODULE handle = NULL;
+            BOOL ret;
 
-        dso = DSO_dsobyaddr(handlersym.sym, DSO_FLAG_NO_UNLOAD_ON_FREE);
-        DSO_free(dso);
+            /*
+             * We don't use the DSO route for WIN32 because there is a better
+             * way
+             */
+            ret = GetModuleHandleEx(GET_MODULE_HANDLE_EX_FLAG_FROM_ADDRESS
+                                    | GET_MODULE_HANDLE_EX_FLAG_PIN,
+                                    handlersym.sym, &handle);
+
+            if (!ret)
+                return 0;
+        }
+# else
+        /*
+         * Deliberately leak a reference to the handler. This will force the
+         * library/code containing the handler to remain loaded until we run the
+         * atexit handler. If -znodelete has been used then this is
+         * unneccessary.
+         */
+        {
+            DSO *dso = NULL;
+
+            dso = DSO_dsobyaddr(handlersym.sym, DSO_FLAG_NO_UNLOAD_ON_FREE);
+            DSO_free(dso);
+        }
+# endif
     }
 #endif