cleanup string handling

RemoteIDModule/RemoteIDModule.ino

@@ -131,52 +131,56 @@ void setup()
 /*
   check parsing of UAS_data, this checks ranges of values to ensure we
   will produce a valid pack
+  returns nullptr on no error, or a string error
  */
 static const char *check_parse(void)
 {
-    static char return_string[50]; //if all errors would occur in this function, it will fit in 50 chars that is also the max for the arm status message
-    strcpy (return_string, "bad ");
+    String ret = "";
 
     {
         ODID_Location_encoded encoded {};
         if (encodeLocationMessage(&encoded, &UAS_data.Location) != ODID_SUCCESS) {
-            strcat(return_string, "LOC ");
+            ret += "LOC ";
         }
     }
     {
         ODID_System_encoded encoded {};
         if (encodeSystemMessage(&encoded, &UAS_data.System) != ODID_SUCCESS) {
-            strcat(return_string, "SYS ");
+            ret += "SYS ";
         }
     }
     {
         ODID_BasicID_encoded encoded {};
         if (UAS_data.BasicIDValid[0] == 1) {
             if (encodeBasicIDMessage(&encoded, &UAS_data.BasicID[0]) != ODID_SUCCESS) {
-                strcat(return_string, "ID_1 ");
+                ret += "ID_1 ";
             }
         }
         memset(&encoded, 0, sizeof(encoded));
         if (UAS_data.BasicIDValid[1] == 1) {
             if (encodeBasicIDMessage(&encoded, &UAS_data.BasicID[1]) != ODID_SUCCESS) {
-                strcat(return_string, "ID_2 ");
+                ret += "ID_2 ";
             }
         }
     }
     {
         ODID_SelfID_encoded encoded {};
         if (encodeSelfIDMessage(&encoded, &UAS_data.SelfID) != ODID_SUCCESS) {
-            strcat(return_string, "SELF_ID ");
+            ret += "SELF_ID ";
         }
     }
     {
         ODID_OperatorID_encoded encoded {};
         if (encodeOperatorIDMessage(&encoded, &UAS_data.OperatorID) != ODID_SUCCESS) {
-            strcat(return_string, "OP_ID ");
+            ret += "OP_ID ";
         }
     }
-    if (strlen(return_string) > 4) { //only return  error messag if one or more encoding functions failed
-        strcat(return_string, "data ");
+    if (ret.length() > 0) {
+        // if all errors would occur in this function, it will fit in
+        // 50 chars that is also the max for the arm status message
+        static char return_string[50];
+        memset(return_string, 0, sizeof(return_string));
+        snprintf(return_string, sizeof(return_string-1), "bad %s data", ret.c_str());
         return return_string;
     }
     return nullptr;

RemoteIDModule/transport.cpp

@@ -45,64 +45,49 @@ uint8_t Transport::arm_status_check(const char *&reason)
         return status;
     }
 
-    char return_string[200]; //make it bigger to accomodate all possible errors
-    memset(return_string, 0, 200);
-    strcpy (return_string, "missing ");
-
-    static char return_string_full[50];
-    memset(return_string_full, 0, 50);
+    String ret = "";
 
     if (last_location_ms == 0 || now_ms - last_location_ms > max_age_location_ms) {
-        strcat(return_string, "LOC ");
+        ret += "LOC ";
     }
     if (!g.have_basic_id_info()) {
         // if there is no basic ID data stored in the parameters give warning. If basic ID data are streamed to RID device,
         // it will store them in the parameters
-        strcat(return_string, "ID ");
+        ret += "ID ";
     }
 
     if (last_self_id_ms == 0  || now_ms - last_self_id_ms > max_age_other_ms) {
-        strcat(return_string, "SELF_ID ");
+        ret += "SELF_ID ";
     }
 
     if (last_operator_id_ms == 0 || now_ms - last_operator_id_ms > max_age_other_ms) {
-        strcat(return_string, "OP_ID ");
+        ret += "OP_ID ";
     }
 
     if (last_system_ms == 0 || now_ms - last_system_ms > max_age_location_ms) {
         // we use location age limit for system as the operator location needs to come in as fast
         // as the vehicle location for FAA standard
-        strcat(return_string, "SYS ");
+        ret += "SYS ";
     }
 
     if (location.latitude == 0 && location.longitude == 0) {
-        if (strcmp(return_string ,"missing ") == 0) {
-            //if the return string only contains the word missing, there is no error.
-            strcpy(return_string, "zero LOC ");
-        }
-        else {
-             strcat(return_string, "zero LOC ");
-        }
+        ret += "LOC ";
     }
 
     if (system.operator_latitude == 0 && system.operator_longitude == 0) {
-        if (strcmp(return_string ,"missing ") == 0) {
-            //if the return string only contains the word missing, there is no error.
-            strcpy(return_string, "zero OP_LOC ");
-        }
-        else {
-             strcat(return_string, "zero OP_LOC ");
-        }
+        ret += "OP_LOC ";
     }
 
-    if (return_string == nullptr && reason == nullptr) {
+    if (ret.length() == 0 && reason == nullptr) {
         status = MAV_ODID_ARM_STATUS_GOOD_TO_ARM;
     } else {
-        if (reason!=nullptr) {
-            strncpy(return_string_full, reason, 49);
+        static char return_string[200];
+        memset(return_string, 0, sizeof(return_string));
+        if (reason != nullptr) {
+            strlcpy(return_string, reason, sizeof(return_string));
         }
-        strncat(return_string_full, return_string, 49 - strlen(return_string_full));
-        reason = return_string_full;
+        strlcat(return_string, ret.c_str(), sizeof(return_string));
+        reason = return_string;
     }
 
     return status;