Fix nasa#2529, Adds snprintf check return value in EVS_SendViaPorts

modules/evs/fsw/src/cfe_evs_task.h

@@ -60,7 +60,7 @@
 #define CFE_EVS_MAX_FILTER_COUNT 65535
 #define CFE_EVS_MAX_SQUELCH_COUNT 255
 #define CFE_EVS_PIPE_NAME "EVS_CMD_PIPE"
-#define CFE_EVS_MAX_PORT_MSG_LENGTH (CFE_MISSION_EVS_MAX_MESSAGE_LENGTH + OS_MAX_API_NAME + 30)
+#define CFE_EVS_MAX_PORT_MSG_LENGTH (CFE_MISSION_EVS_MAX_MESSAGE_LENGTH + OS_MAX_API_NAME + 19)
 
 /* Since CFE_EVS_MAX_PORT_MSG_LENGTH is the size of the buffer that is sent to
  * print out (using OS_printf), we need to check to make sure that the buffer
@@ -70,6 +70,14 @@
 #error CFE_EVS_MAX_PORT_MSG_LENGTH cannot be greater than OS_BUFFER_SIZE!
 #endif
 
+/* The buffer needs to have at least 11 extra characters to accommodate the format
+ * string "EVS Port%u %s\n" used in downstream processing for sending messages via ports.
+ * If the difference between OS_BUFFER_SIZE and CFE_EVS_MAX_PORT_MSG_LENGTH is less than 11,
+ * it could result in the truncation of the new line character appended downstream. */
+#if OS_BUFFER_SIZE - CFE_EVS_MAX_PORT_MSG_LENGTH < 11
+#error CFE_EVS_MAX_PORT_MSG_LENGTH exceeds the maximum allowable length to prevent null character truncation!
+#endif
+
 /************************ Internal Structure Definitions *****************************/
 
 typedef struct