AP_GPS: protect parameters from being accessed externally

backends become friends so they can continue to access parameters held in frontend
get_rate_ms made private because only used by frontend
Also moved static arrays higher in cpp file

libraries/AP_GPS/AP_GPS.cpp

@@ -44,6 +44,13 @@
 
 extern const AP_HAL::HAL &hal;
 
+// baudrates to try to detect GPSes with
+const uint32_t AP_GPS::_baudrates[] = {4800U, 19200U, 38400U, 115200U, 57600U, 9600U, 230400U};
+
+// initialisation blobs to send to the GPS to try to get it into the
+// right mode
+const char AP_GPS::_initialisation_blob[] = UBLOX_SET_BINARY MTK_SET_BINARY SIRF_SET_BINARY;
+
 // table of user settable parameters
 const AP_Param::GroupInfo AP_GPS::var_info[] = {
     // @Param: TYPE
@@ -270,8 +277,6 @@ void AP_GPS::init(DataFlash_Class *dataflash, const AP_SerialManager& serial_man
     }
 }
 
-// baudrates to try to detect GPSes with
-const uint32_t AP_GPS::_baudrates[] = {4800U, 19200U, 38400U, 115200U, 57600U, 9600U, 230400U};
 // return number of active GPS sensors. Note that if the first GPS
 // is not present but the 2nd is then we return 2. Note that a blended
 // GPS solution is treated as an additional sensor.
@@ -284,9 +289,6 @@ uint8_t AP_GPS::num_sensors(void) const
     }
 }
 
-// initialisation blobs to send to the GPS to try to get it into the
-// right mode
-const char AP_GPS::_initialisation_blob[] = UBLOX_SET_BINARY MTK_SET_BINARY SIRF_SET_BINARY;
 bool AP_GPS::speed_accuracy(uint8_t instance, float &sacc) const
 {
     if (state[instance].have_speed_accuracy) {

libraries/AP_GPS/AP_GPS.h

@@ -47,13 +47,21 @@ class AP_GPS
 {
 public:
 
-    /// Startup initialisation.
-    void init(DataFlash_Class *dataflash, const AP_SerialManager& serial_manager);
+    friend class AP_GPS_ERB;
+    friend class AP_GPS_GSOF;
+    friend class AP_GPS_MAV;
+    friend class AP_GPS_MTK;
+    friend class AP_GPS_MTK19;
+    friend class AP_GPS_NMEA;
+    friend class AP_GPS_NOVA;
+    friend class AP_GPS_PX4;
+    friend class AP_GPS_QURT;
+    friend class AP_GPS_SBF;
+    friend class AP_GPS_SBP;
+    friend class AP_GPS_SIRF;
+    friend class AP_GPS_UBLOX;
+    friend class AP_GPS_Backend;
 
-    /// Update GPS state based on possible bytes received from the module.
-    /// This routine must be called periodically (typically at 10Hz or
-    /// more) to process incoming data.
-    void update(void);
     // constructor
 	AP_GPS();
 
@@ -134,6 +142,14 @@ public:
         uint32_t last_gps_time_ms;          ///< the system time we got the last GPS timestamp, milliseconds
     };
 
+    /// Startup initialisation.
+    void init(DataFlash_Class *dataflash, const AP_SerialManager& serial_manager);
+
+    /// Update GPS state based on possible bytes received from the module.
+    /// This routine must be called periodically (typically at 10Hz or
+    /// more) to process incoming data.
+    void update(void);
+
     // Pass mavlink data to message handlers (for MAV type)
     void handle_msg(const mavlink_message_t *msg);
 
@@ -279,15 +295,6 @@ public:
         return last_message_time_ms(primary_instance);
     }
 
-    // convert GPS week and millis to unix epoch in ms
-    static uint64_t time_epoch_convert(uint16_t gps_week, uint32_t gps_ms);
-    
-    // return last fix time since the 1/1/1970 in microseconds
-    uint64_t time_epoch_usec(uint8_t instance);
-    uint64_t time_epoch_usec(void) { 
-        return time_epoch_usec(primary_instance); 
-    }
-
 	// return true if the GPS supports vertical velocity values
     bool have_vertical_velocity(uint8_t instance) const { 
         return state[instance].have_vertical_velocity; 
@@ -300,9 +307,6 @@ public:
     float get_lag(uint8_t instance) const;
     float get_lag(void) const { return get_lag(primary_instance); }
 
-    // return gps update rate in milliseconds
-    uint16_t get_rate_ms(uint8_t instance) const;
-
     // return a 3D vector defining the offset of the GPS antenna in meters relative to the body frame origin
     const Vector3f &get_antenna_offset(uint8_t instance) const;
 
@@ -313,9 +317,47 @@ public:
 
     // set accuracy for HIL
     void setHIL_Accuracy(uint8_t instance, float vdop, float hacc, float vacc, float sacc, bool _have_vertical_velocity, uint32_t sample_ms);
-    
+
+    // lock out a GPS port, allowing another application to use the port
+    void lock_port(uint8_t instance, bool locked);
+
+    //Inject a packet of raw binary to a GPS
+    void inject_data(uint8_t *data, uint8_t len);
+    void inject_data(uint8_t instance, uint8_t *data, uint8_t len);
+
+    //MAVLink Status Sending
+    void send_mavlink_gps_raw(mavlink_channel_t chan);
+    void send_mavlink_gps2_raw(mavlink_channel_t chan);
+
+    void send_mavlink_gps_rtk(mavlink_channel_t chan);
+    void send_mavlink_gps2_rtk(mavlink_channel_t chan);
+
+    // Returns the index of the first unconfigured GPS (returns GPS_ALL_CONFIGURED if all instances report as being configured)
+    uint8_t first_unconfigured_gps(void) const;
+    void broadcast_first_configuration_failure_reason(void) const;
+
+    // return true if all GPS instances have finished configuration
+    bool all_configured(void) const {
+        return first_unconfigured_gps() == GPS_ALL_CONFIGURED;
+    }
+
+    // handle sending of initialisation strings to the GPS - only used by backends
+    void send_blob_start(uint8_t instance, const char *_blob, uint16_t size);
+    void send_blob_update(uint8_t instance);
+
+    // return last fix time since the 1/1/1970 in microseconds
+    uint64_t time_epoch_usec(uint8_t instance);
+    uint64_t time_epoch_usec(void) {
+        return time_epoch_usec(primary_instance);
+    }
+
+    // convert GPS week and millis to unix epoch in ms
+    static uint64_t time_epoch_convert(uint16_t gps_week, uint32_t gps_ms);
+
     static const struct AP_Param::GroupInfo var_info[];
 
+protected:
+
     // dataflash for logging, if available
     DataFlash_Class *_DataFlash;
 
@@ -339,34 +381,10 @@ public:
     AP_Int8 _blend_mask;
     AP_Float _blend_tc;
 
-    // handle sending of initialisation strings to the GPS
-    void send_blob_start(uint8_t instance, const char *_blob, uint16_t size);
-    void send_blob_update(uint8_t instance);
-
-    // lock out a GPS port, allowing another application to use the port
-    void lock_port(uint8_t instance, bool locked);
-
-    //Inject a packet of raw binary to a GPS
-    void inject_data(uint8_t *data, uint8_t len);
-    void inject_data(uint8_t instance, uint8_t *data, uint8_t len);
-
-    //MAVLink Status Sending
-    void send_mavlink_gps_raw(mavlink_channel_t chan);
-    void send_mavlink_gps2_raw(mavlink_channel_t chan);
-
-    void send_mavlink_gps_rtk(mavlink_channel_t chan);
-    void send_mavlink_gps2_rtk(mavlink_channel_t chan);
-
-    // Returns the index of the first unconfigured GPS (returns GPS_ALL_CONFIGURED if all instances report as being configured)
-    uint8_t first_unconfigured_gps(void) const;
-    void broadcast_first_configuration_failure_reason(void) const;
-
-    // return true if all GPS instances have finished configuration
-    bool all_configured(void) const {
-        return first_unconfigured_gps() == GPS_ALL_CONFIGURED;
-    }
-    
 private:
+    // return gps update rate in milliseconds
+    uint16_t get_rate_ms(uint8_t instance) const;
+
     struct GPS_timing {
         // the time we got our last fix in system milliseconds
         uint32_t last_fix_time_ms;