DataFlash: rotate files when vehicle is disarmed

libraries/DataFlash/DataFlash.cpp

@@ -31,7 +31,14 @@ const AP_Param::GroupInfo DataFlash_Class::var_info[] = {
     // @Values: 0:Disabled,1:Enabled
     // @User: Standard
     AP_GROUPINFO("_REPLAY",  3, DataFlash_Class, _params.log_replay,       0),
-    
+
+    // @Param: _FILE_DSRMROT
+    // @DisplayName: Stop logging to current file on disarm
+    // @Description: When set, the current log file is closed when the vehicle is disarmed.  If LOG_DISARMED is set then a fresh log will be opened.
+    // @Values: 0:Disabled,1:Enabled
+    // @User: Standard
+    AP_GROUPINFO("_FILE_DSRMROT",  4, DataFlash_Class, _params.file_disarm_rot,       0),
+
     AP_GROUPEND
 };
 
@@ -78,8 +85,13 @@ void DataFlash_Class::set_vehicle_armed(const bool armed_state)
         // no change in status
         return;
     }
-
     _armed = armed_state;
+
+    if (!_armed) {
+        // went from armed to disarmed
+        FOR_EACH_BACKEND(vehicle_was_disarmed());
+    }
+
 }
 
 

libraries/DataFlash/DataFlash.h

@@ -192,6 +192,7 @@ public:
     struct {
         AP_Int8 backend_types;
         AP_Int8 file_bufsize; // in kilobytes
+        AP_Int8 file_disarm_rot;
         AP_Int8 log_disarmed;
         AP_Int8 log_replay;
     } _params;

libraries/DataFlash/DataFlash_Backend.h

@@ -121,6 +121,8 @@ public:
     virtual bool logging_enabled() const = 0;
     virtual bool logging_failed() const = 0;
 
+    virtual void vehicle_was_disarmed() { };
+
 protected:
     uint32_t dropped;
     uint8_t internal_errors; // uint8_t - wishful thinking?

libraries/DataFlash/DataFlash_File.cpp

@@ -1108,4 +1108,14 @@ bool DataFlash_File::logging_failed() const
 }
 
 
+void DataFlash_File::vehicle_was_disarmed()
+{
+    if (_front._params.file_disarm_rot) {
+        // rotate our log.  Closing the current one and letting the
+        // logging restart naturally based on log_disarmed should do
+        // the trick:
+        stop_logging();
+    }
+}
+
 #endif // HAL_OS_POSIX_IO

libraries/DataFlash/DataFlash_File.h

@@ -70,6 +70,8 @@ public:
     bool logging_enabled() const;
     bool logging_failed() const;
 
+    void vehicle_was_disarmed() override;
+
 private:
     int _write_fd;
     int _read_fd;