Fix #944, add OS_API_Teardown

This cleans up all OSAL resources as best as possible, ideally leaving
the system in a state where OS_API_Init() may be invoked again.

src/os/inc/osapi-common.h

@@ -138,6 +138,33 @@ void OS_Application_Run(void);
  */
 int32 OS_API_Init(void);
 
+/*-------------------------------------------------------------------------------------*/
+/**
+ * @brief Teardown/de-initialization of OSAL API
+ *
+ * This is the inverse of OS_API_Init().  It will release all OS resources and
+ * return the system to a state similar to what it was prior to invoking
+ * OS_API_Init() initially.
+ *
+ * Normally for embedded applications, the OSAL is initialized after boot and will remain
+ * initialized in memory until the processor is rebooted.  However for testing and
+ * developement purposes, it is potentially useful to reset back to initial conditions.
+ *
+ * For testing purposes, this API is designed/intended to be compatible with the
+ * UtTest_AddTeardown() routine provided by the UT-Assert subsystem.
+ *
+ * @note This is a "best-effort" routine and it may not always be possible/guaranteed
+ * to recover all resources, particularly in the case of off-nominal conditions, or if
+ * a resource is used outside of OSAL.
+ *
+ * For example, while this will attempt to unload all dynamically-loaded modules, doing
+ * so may not be possible and/or may induce undefined behavior if resources are in use by
+ * tasks/functions outside of OSAL.
+ *
+ * @return None
+ */
+void OS_API_Teardown(void);
+
 /*-------------------------------------------------------------------------------------*/
 /**
  * @brief Background thread implementation - waits forever for events to occur.

src/os/shared/src/osapi-common.c

@@ -219,6 +219,28 @@ int32 OS_API_Init(void)
     return (return_code);
 } /* end OS_API_Init */
 
+/*----------------------------------------------------------------
+ *
+ * Function: OS_API_Teardown
+ *
+ *  Purpose: Implemented per public OSAL API
+ *           See description in API and header file for detail
+ *
+ *-----------------------------------------------------------------*/
+void OS_API_Teardown(void)
+{
+    /*
+     * This should delete any remaining user-created objects/tasks
+     */
+    OS_DeleteAllObjects();
+
+    /*
+     * This should cause the "internal" objects (e.g. console utility task)
+     * to exit, and will prevent any new objects from being created.
+     */
+    OS_ApplicationShutdown(true);
+}
+
 /*----------------------------------------------------------------
  *
  * Function: OS_RegisterEventHandler