GCS_MAVLink: treat clear-all as zero-item-upload

these would appear to be identical operations.

libraries/GCS_MAVLink/MissionItemProtocol.cpp

@@ -29,13 +29,10 @@ void MissionItemProtocol::init_send_requests(GCS_MAVLINK &_link,
     mission_request_warning_sent = false;
 }
 
-void MissionItemProtocol::handle_mission_clear_all(const GCS_MAVLINK &_link,
+void MissionItemProtocol::handle_mission_clear_all(GCS_MAVLINK &_link,
                                                    const mavlink_message_t &msg)
 {
-    bool success = true;
-    success = success && !receiving;
-    success = success && clear_all_items();
-    send_mission_ack(_link, msg, success ? MAV_MISSION_ACCEPTED : MAV_MISSION_ERROR);
+    handle_mission_count(_link, 0, msg);
 }
 
 bool MissionItemProtocol::mavlink2_requirement_met(const GCS_MAVLINK &_link, const mavlink_message_t &msg) const
@@ -55,6 +52,13 @@ bool MissionItemProtocol::mavlink2_requirement_met(const GCS_MAVLINK &_link, con
 void MissionItemProtocol::handle_mission_count(
     GCS_MAVLINK &_link,
     const mavlink_mission_count_t &packet,
+    const mavlink_message_t &msg) {
+    handle_mission_count(_link, packet.count, msg);
+}
+
+void MissionItemProtocol::handle_mission_count(
+    GCS_MAVLINK &_link,
+    uint16_t count,
     const mavlink_message_t &msg)
 {
     if (!mavlink2_requirement_met(_link, msg)) {
@@ -77,29 +81,29 @@ void MissionItemProtocol::handle_mission_count(
         link = nullptr;
     }
 
-    if (packet.count > max_items()) {
+    if (count > max_items()) {
         // FIXME: different items take up different storage space!
         send_mission_ack(_link, msg, MAV_MISSION_NO_SPACE);
         GCS_SEND_TEXT(MAV_SEVERITY_WARNING, "Only %u items are supported", (unsigned)max_items());
         return;
     }
 
-    MAV_MISSION_RESULT ret_alloc = allocate_receive_resources(packet.count);
+    MAV_MISSION_RESULT ret_alloc = allocate_receive_resources(count);
     if (ret_alloc != MAV_MISSION_ACCEPTED) {
         send_mission_ack(_link, msg, ret_alloc);
         return;
     }
 
-    truncate(packet);
+    truncate(count);
 
-    if (packet.count == 0) {
+    if (count == 0) {
         // no requests to send...
         transfer_is_complete(_link, msg);
         return;
     }
 
     // start waypoint receiving
-    init_send_requests(_link, msg, 0, packet.count-1);
+    init_send_requests(_link, msg, 0, count-1);
 }
 
 void MissionItemProtocol::handle_mission_request_list(

libraries/GCS_MAVLink/MissionItemProtocol.h

@@ -49,7 +49,7 @@ class MissionItemProtocol
     void handle_mission_item(const mavlink_message_t &msg,
                              const mavlink_mission_item_int_t &cmd);
 
-    void handle_mission_clear_all(const GCS_MAVLINK &link,
+    void handle_mission_clear_all(GCS_MAVLINK &link,
                                   const mavlink_message_t &msg);
 
     void queued_request_send();
@@ -73,13 +73,13 @@ class MissionItemProtocol
     // item request to the GCS:
     virtual ap_message next_item_ap_message_id() const = 0;
 
-    virtual bool clear_all_items() = 0;
-
     uint16_t        request_last; // last request index
 
 private:
 
-    virtual void truncate(const mavlink_mission_count_t &packet) = 0;
+    void handle_mission_count(class GCS_MAVLINK &link, uint16_t count, const mavlink_message_t &msg);
+
+    virtual void truncate(uint16_t count) = 0;
 
     uint16_t        request_i; // request index
 

libraries/GCS_MAVLink/MissionItemProtocol_Fence.cpp

@@ -199,16 +199,11 @@ uint16_t MissionItemProtocol_Fence::max_items() const
     return _fence.polyfence().max_items();
 }
 
-void MissionItemProtocol_Fence::truncate(const mavlink_mission_count_t &packet)
+void MissionItemProtocol_Fence::truncate(uint16_t count)
 {
     // FIXME: validate packet.count is same as allocated number of items
 }
 
-bool MissionItemProtocol_Fence::clear_all_items()
-{
-    return _fence.polyfence().write_fence(nullptr, 0);
-}
-
 MAV_MISSION_RESULT MissionItemProtocol_Fence::allocate_receive_resources(const uint16_t count)
 {
     if (_new_items != nullptr) {

libraries/GCS_MAVLink/MissionItemProtocol_Fence.h

@@ -15,7 +15,7 @@ class MissionItemProtocol_Fence : public MissionItemProtocol {
         return MAV_MISSION_TYPE_FENCE;
     }
 
-    void truncate(const mavlink_mission_count_t &packet) override;
+    void truncate(uint16_t count) override;
     MAV_MISSION_RESULT complete(const GCS_MAVLINK &_link) override;
     void timeout() override;
 
@@ -31,7 +31,6 @@ class MissionItemProtocol_Fence : public MissionItemProtocol {
     ap_message next_item_ap_message_id() const override {
         return MSG_NEXT_MISSION_REQUEST_FENCE;
     }
-    bool clear_all_items() override WARN_IF_UNUSED;
 
 private:
     class AC_Fence &_fence;

libraries/GCS_MAVLink/MissionItemProtocol_Rally.cpp

@@ -49,12 +49,6 @@ MAV_MISSION_RESULT MissionItemProtocol_Rally::complete(const GCS_MAVLINK &_link)
     return MAV_MISSION_ACCEPTED;
 }
 
-bool MissionItemProtocol_Rally::clear_all_items()
-{
-    rally.truncate(0);
-    return true;
-}
-
 MAV_MISSION_RESULT MissionItemProtocol_Rally::convert_MISSION_ITEM_INT_to_RallyLocation(const mavlink_mission_item_int_t &cmd, RallyLocation &ret)
 {
     if (cmd.command != MAV_CMD_NAV_RALLY_POINT) {
@@ -184,9 +178,9 @@ void MissionItemProtocol_Rally::timeout()
     link->send_text(MAV_SEVERITY_WARNING, "Rally upload timeout");
 }
 
-void MissionItemProtocol_Rally::truncate(const mavlink_mission_count_t &packet)
+void MissionItemProtocol_Rally::truncate(uint16_t count)
 {
-    rally.truncate(packet.count);
+    rally.truncate(count);
 }
 
 #endif  // HAL_GCS_ENABLED && HAL_RALLY_ENABLED

libraries/GCS_MAVLink/MissionItemProtocol_Rally.h

@@ -10,7 +10,7 @@ class MissionItemProtocol_Rally : public MissionItemProtocol {
 public:
     MissionItemProtocol_Rally(class AP_Rally &_rally) :
         rally(_rally) {}
-    void truncate(const mavlink_mission_count_t &packet) override;
+    void truncate(uint16_t count) override;
     MAV_MISSION_TYPE mission_type() const override { return MAV_MISSION_TYPE_RALLY; }
 
     MAV_MISSION_RESULT complete(const GCS_MAVLINK &_link) override;
@@ -28,7 +28,6 @@ class MissionItemProtocol_Rally : public MissionItemProtocol {
     ap_message next_item_ap_message_id() const override {
         return MSG_NEXT_MISSION_REQUEST_RALLY;
     }
-    bool clear_all_items() override WARN_IF_UNUSED;
 
 private:
     AP_Rally &rally;

libraries/GCS_MAVLink/MissionItemProtocol_Waypoints.cpp

@@ -50,11 +50,6 @@ MAV_MISSION_RESULT MissionItemProtocol_Waypoints::append_item(const mavlink_miss
     return MAV_MISSION_ACCEPTED;
 }
 
-bool MissionItemProtocol_Waypoints::clear_all_items()
-{
-    return mission.clear();
-}
-
 MAV_MISSION_RESULT MissionItemProtocol_Waypoints::complete(const GCS_MAVLINK &_link)
 {
     _link.send_text(MAV_SEVERITY_INFO, "Flight plan received");
@@ -141,10 +136,10 @@ void MissionItemProtocol_Waypoints::timeout()
     link->send_text(MAV_SEVERITY_WARNING, "Mission upload timeout");
 }
 
-void MissionItemProtocol_Waypoints::truncate(const mavlink_mission_count_t &packet)
+void MissionItemProtocol_Waypoints::truncate(uint16_t count)
 {
     // new mission arriving, truncate mission to be the same length
-    mission.truncate(packet.count);
+    mission.truncate(count);
 }
 
 #endif  // HAL_GCS_ENABLED && AP_MISSION_ENABLED

libraries/GCS_MAVLink/MissionItemProtocol_Waypoints.h

@@ -23,13 +23,10 @@ class MissionItemProtocol_Waypoints : public MissionItemProtocol {
     // truncate() is called to set the absolute number of items.  It
     // must be less than or equal to the current number of items (you
     // can't truncate-to a longer list)
-    void truncate(const mavlink_mission_count_t &packet) override;
+    void truncate(uint16_t count) override;
 
 protected:
 
-    // clear_all_items() is called to clear all items on the vehicle
-    bool clear_all_items() override WARN_IF_UNUSED;
-
     // next_item_ap_message_id returns an item from the ap_message
     // enumeration which (when acted upon by the GCS class) will send
     // a mavlink message to the GCS requesting it upload the next