[onert] Add API function for retrieving last error message

This commit adds dedicated API function nnfw_get_last_error_message()
for retrieving last error message in case when other functions return
status code other than NNFW_STATUS_NO_ERROR.

ONE-DCO-1.0-Signed-off-by: Arkadiusz Bokowy <a.bokowy@samsung.com>

Author: arkq

runtime/onert/api/nnfw/include/nnfw.h

@@ -212,6 +212,19 @@ NNFW_STATUS nnfw_create_session(nnfw_session **session);
  */
 NNFW_STATUS nnfw_close_session(nnfw_session *session);
 
+/**
+ * @brief Get the last error message
+ *
+ * This function retrieves the last error message occurred in the session.
+ *
+ * @param[in]  session The session to get the last error message from
+ * @param[out] buffer  Buffer to store the last error message string
+ * @param[in]  length  The size of the buffer
+ * @return     @c NNFW_STATUS_NO_ERROR if successful, otherwise appropriate
+ *             error code and the content of buffer is not changed.
+ */
+NNFW_STATUS nnfw_get_last_error_message(nnfw_session *session, char *buffer, size_t length);
+
 /**
  * @brief     Load model from path to model or nnpackage
  *

runtime/onert/api/nnfw/src/APIImpl.cc

@@ -69,6 +69,12 @@ NNFW_STATUS nnfw_close_session(nnfw_session *session)
   return NNFW_STATUS_NO_ERROR;
 }
 
+NNFW_STATUS nnfw_get_last_error_message(nnfw_session *session, char *buffer, size_t length)
+{
+  NNFW_RETURN_ERROR_IF_NULL(session);
+  return reinterpret_cast<Session *>(session)->get_last_error_message(buffer, length);
+}
+
 NNFW_STATUS nnfw_load_model_from_file(nnfw_session *session, const char *path)
 {
   NNFW_RETURN_ERROR_IF_NULL(session);