update pull request

Author: Shu0T1an ChenG

portsyncd/linksync.cpp

@@ -61,18 +61,24 @@ LinkSync::LinkSync(DBConnector *appl_db, DBConnector *state_db) :
             cmd = "cat /sys/class/net/" + key + "/operstate";
             try
             {
-                exec(cmd, res);
+                EXEC_WITH_ERROR_THROW(cmd, res);
             }
             catch (...)
             {
                 SWSS_LOG_WARN("Failed to get %s oper status", key.c_str());
                 continue;
             }
+
             /* Remove the trailing newline */
-            if (res.length() > 1 && res.at(res.length() - 1) == '\n')
+            if (res.length() >= 1 && res.at(res.length() - 1) == '\n')
             {
                 res.erase(res.length() - 1);
                 /* The value of operstate will be either up or down */
+                if (res != "up" && res != "down")
+                {
+                    SWSS_LOG_WARN("Unknown %s oper status %s",
+                            key.c_str(), res.c_str());
+                }
                 FieldValueTuple fv("oper_status", res);
                 vector<FieldValueTuple> fvs;
                 fvs.push_back(fv);