GCS_MAVLink: expose functions to convert fence and rally to mavlink

this allows for the @MISSION filesystem to download data in the
current mavlink format

libraries/GCS_MAVLink/MissionItemProtocol_Fence.cpp

@@ -2,20 +2,25 @@
 
 #include <AC_Fence/AC_Fence.h>
 
-MAV_MISSION_RESULT MissionItemProtocol_Fence::get_item(const GCS_MAVLINK &_link,
+/*
-                                                       const mavlink_message_t &msg,
+  public function to format mission item as mavlink_mission_item_int_t
-                                                       const mavlink_mission_request_int_t &packet,
+ */
-                                                       mavlink_mission_item_int_t &ret_packet)
+bool MissionItemProtocol_Fence::get_item_as_mission_item(uint16_t seq,
+                                                         mavlink_mission_item_int_t &ret_packet)
 {
-    const uint8_t num_stored_items = _fence.polyfence().num_stored_items();
+    AC_Fence *fence = AP::fence();
-    if (packet.seq > num_stored_items) {
+    if (fence == nullptr) {
-        return MAV_MISSION_INVALID_SEQUENCE;
+        return false;
+    }
+    const uint8_t num_stored_items = fence->polyfence().num_stored_items();
+    if (seq > num_stored_items) {
+        return false;
     }
 
     AC_PolyFenceItem fenceitem;
 
-    if (!_fence.polyfence().get_item(packet.seq, fenceitem)) {
+    if (!fence->polyfence().get_item(seq, fenceitem)) {
-        return MAV_MISSION_ERROR;
+        return false;
     }
 
     MAV_CMD ret_cmd = MAV_CMD_NAV_FENCE_POLYGON_VERTEX_INCLUSION; // initialised to avoid compiler warning
@@ -41,7 +46,7 @@ MAV_MISSION_RESULT MissionItemProtocol_Fence::get_item(const GCS_MAVLINK &_link,
         p1 = fenceitem.radius;
         break;
     case AC_PolyFenceType::END_OF_STORAGE:
-        return MAV_MISSION_ERROR;
+        return false;
     }
 
     ret_packet.command = ret_cmd;
@@ -50,6 +55,23 @@ MAV_MISSION_RESULT MissionItemProtocol_Fence::get_item(const GCS_MAVLINK &_link,
     ret_packet.y = fenceitem.loc.y;
     ret_packet.z = 0;
 
+    return true;
+}
+
+MAV_MISSION_RESULT MissionItemProtocol_Fence::get_item(const GCS_MAVLINK &_link,
+                                                       const mavlink_message_t &msg,
+                                                       const mavlink_mission_request_int_t &packet,
+                                                       mavlink_mission_item_int_t &ret_packet)
+{
+    const uint8_t num_stored_items = _fence.polyfence().num_stored_items();
+    if (packet.seq > num_stored_items) {
+        return MAV_MISSION_INVALID_SEQUENCE;
+    }
+
+    if (!get_item_as_mission_item(packet.seq, ret_packet)) {
+        return MAV_MISSION_ERROR;
+    }
+
     return MAV_MISSION_ACCEPTED;
 }
 

libraries/GCS_MAVLink/MissionItemProtocol_Fence.h

@@ -17,6 +17,11 @@ public:
     MAV_MISSION_RESULT complete(const GCS_MAVLINK &_link) override;
     void timeout() override;
 
+    /*
+      static function to format mission item as mavlink_mission_item_int_t
+    */
+    static bool get_item_as_mission_item(uint16_t seq, mavlink_mission_item_int_t &ret_packet);
+    
 protected:
 
     ap_message next_item_ap_message_id() const override {

libraries/GCS_MAVLink/MissionItemProtocol_Rally.cpp

@@ -73,15 +73,18 @@ MAV_MISSION_RESULT MissionItemProtocol_Rally::convert_MISSION_ITEM_INT_to_RallyL
     return MAV_MISSION_ACCEPTED;
 }
 
-MAV_MISSION_RESULT MissionItemProtocol_Rally::get_item(const GCS_MAVLINK &_link,
+/*
-                                                       const mavlink_message_t &msg,
+  static function to get rally item as mavlink_mission_item_int_t
-                                                       const mavlink_mission_request_int_t &packet,
+ */
-                                                       mavlink_mission_item_int_t &ret_packet)
+bool MissionItemProtocol_Rally::get_item_as_mission_item(uint16_t seq,
+                                                         mavlink_mission_item_int_t &ret_packet)
 {
+    auto *rallyp = AP::rally();
+
     RallyLocation rallypoint;
 
-    if (!rally.get_rally_point_with_index(packet.seq, rallypoint)) {
+    if (rallyp == nullptr || !rallyp->get_rally_point_with_index(seq, rallypoint)) {
-        return MAV_MISSION_INVALID_SEQUENCE;
+        return false;
     }
 
     ret_packet.frame = MAV_FRAME_GLOBAL_RELATIVE_ALT;
@@ -90,6 +93,17 @@ MAV_MISSION_RESULT MissionItemProtocol_Rally::get_item(const GCS_MAVLINK &_link,
     ret_packet.y = rallypoint.lng;
     ret_packet.z = rallypoint.alt;
 
+    return true;
+}
+
+MAV_MISSION_RESULT MissionItemProtocol_Rally::get_item(const GCS_MAVLINK &_link,
+                                                       const mavlink_message_t &msg,
+                                                       const mavlink_mission_request_int_t &packet,
+                                                       mavlink_mission_item_int_t &ret_packet)
+{
+    if (!get_item_as_mission_item(packet.seq, ret_packet)) {
+        return MAV_MISSION_INVALID_SEQUENCE;
+    }
     return MAV_MISSION_ACCEPTED;
 }
 

libraries/GCS_MAVLink/MissionItemProtocol_Rally.h

@@ -12,6 +12,11 @@ public:
     MAV_MISSION_RESULT complete(const GCS_MAVLINK &_link) override;
     void timeout() override;
 
+    /*
+      static function to get rally item as mavlink_mission_item_int_t
+    */
+    static bool get_item_as_mission_item(uint16_t seq, mavlink_mission_item_int_t &ret_packet);
+    
 protected:
 
     ap_message next_item_ap_message_id() const override {