fix nasa#1055 - CFE_SB_ReceiveBuffer stub returns timeout or empty if…

… no buffer

fsw/cfe-core/ut-stubs/ut_sb_stubs.c

@@ -447,14 +447,16 @@ int32 CFE_SB_RcvMsg(CFE_SB_Buffer_t **BufPtr,
 **
 ** \par Description
 **        This function is used to mimic the response of the cFE SB function
-**        CFE_SB_ReceiveBuffer.  By default it will return the TIMEOUT error response,
-**        unless the test setup sequence has indicated otherwise.
+**        CFE_SB_ReceiveBuffer.
 **
 ** \par Assumptions, External Events, and Notes:
 **        None
 **
 ** \returns
-**        Returns CFE_SUCCESS or overridden unit test value
+**        If the return value has not been overridden, returns CFE_SUCCESS if there
+**        is a buffer defined by UT_SetDataBuffer. If no buffer was defined,
+**        either CFE_SB_TIME_OUT (if the TimeOut parameter is > 0) or CFE_SB_NO_MESSAGE
+**        is returned. If the return value has been overridden,
 **
 ******************************************************************************/
 int32 CFE_SB_ReceiveBuffer(CFE_SB_Buffer_t **BufPtr,
@@ -471,7 +473,18 @@ int32 CFE_SB_ReceiveBuffer(CFE_SB_Buffer_t **BufPtr,
 
     if (status >= 0)
     {
-        UT_Stub_CopyToLocal(UT_KEY(CFE_SB_ReceiveBuffer), (uint8*)BufPtr, sizeof(*BufPtr));
+        if(UT_Stub_CopyToLocal(UT_KEY(CFE_SB_ReceiveBuffer), (uint8*)BufPtr, sizeof(*BufPtr)) <= 0)
+        {
+            /* no buffer provided, return a non-success return code */
+            if (TimeOut == CFE_SB_PEND_FOREVER)
+            {
+                return CFE_SB_NO_MESSAGE;
+            }
+            else
+            {
+                return CFE_SB_TIME_OUT;
+            }
+        }
     }
 
     return status;