examples: change mavftp class to be a python3 library with a simple API.

The library can be called directly and it is a mavftp application
  the application contains documented argparse arguments
Add a example that uses the library

examples/mavftp_example.py

@@ -0,0 +1,214 @@
+#!/usr/bin/env python3
+
+'''
+MAVLink File Transfer Protocol support example
+
+SPDX-FileCopyrightText: 2024 Amilcar Lucas
+
+SPDX-License-Identifier: GPL-3.0-or-later
+'''
+
+from argparse import ArgumentParser
+
+from logging import basicConfig as logging_basicConfig
+from logging import getLevelName as logging_getLevelName
+
+from logging import debug as logging_debug
+from logging import info as logging_info
+from logging import error as logging_error
+
+import os
+import sys
+import requests
+import time
+
+
+from pymavlink import mavutil
+from pymavlink import mavftp
+
+
+if __name__ == "__main__":
+
+    def argument_parser():
+        """
+        Parses command-line arguments for the script.
+        """
+        parser = ArgumentParser(description='This main is just an example, adapt it to your needs')
+        parser.add_argument("--baudrate", type=int, default=115200,
+                            help="master port baud rate. Defaults to %(default)s")
+        parser.add_argument("--device", type=str, default='',
+                            help="serial device. For windows use COMx where x is the port number. "
+                                 "For Unix use /dev/ttyUSBx where x is the port number. Defaults to autodetection")
+        parser.add_argument("--source-system", dest='SOURCE_SYSTEM', type=int, default=250,
+                            help='MAVLink source system for this GCS. Defaults to %(default)s')
+        parser.add_argument("--loglevel", default="INFO",
+                            help="log level. Defaults to %(default)s")
+
+        return parser.parse_args()
+
+
+    def auto_detect_serial():
+        preferred_ports = [
+            '*FTDI*',
+            "*3D*",
+            "*USB_to_UART*",
+            '*Ardu*',
+            '*PX4*',
+            '*Hex_*',
+            '*Holybro_*',
+            '*mRo*',
+            '*FMU*',
+            '*Swift-Flyer*',
+            '*Serial*',
+            '*CubePilot*',
+            '*Qiotek*',
+        ]
+        serial_list = mavutil.auto_detect_serial(preferred_list=preferred_ports)
+        serial_list.sort(key=lambda x: x.device)
+
+        # remove OTG2 ports for dual CDC
+        if len(serial_list) == 2 and serial_list[0].device.startswith("/dev/serial/by-id"):
+            if serial_list[0].device[:-1] == serial_list[1].device[0:-1]:
+                serial_list.pop(1)
+
+        return serial_list
+
+
+    def auto_connect(device):
+        comport = None
+        if device:
+            comport = mavutil.SerialPort(device=device, description=device)
+        else:
+            autodetect_serial = auto_detect_serial()
+            if autodetect_serial:
+                # Resolve the soft link if it's a Linux system
+                if os.name == 'posix':
+                    try:
+                        dev = autodetect_serial[0].device
+                        logging_debug("Auto-detected device %s", dev)
+                        # Get the directory part of the soft link
+                        softlink_dir = os.path.dirname(dev)
+                        # Resolve the soft link and join it with the directory part
+                        resolved_path = os.path.abspath(os.path.join(softlink_dir, os.readlink(dev)))
+                        autodetect_serial[0].device = resolved_path
+                        logging_debug("Resolved soft link %s to %s", dev, resolved_path)
+                    except OSError:
+                        pass # Not a soft link, proceed with the original device path
+                comport = autodetect_serial[0]
+            else:
+                logging_error("No serial ports found. Please connect a flight controller and try again.")
+                sys.exit(1)
+        return comport
+
+
+    def wait_heartbeat(m):
+        '''wait for a heartbeat so we know the target system IDs'''
+        logging_info("Waiting for flight controller heartbeat")
+        m.wait_heartbeat()
+        logging_info("Got heartbeat from system %u, component %u", m.target_system, m.target_system)
+
+
+    def delete_local_file_if_exists(filename):
+        if os.path.exists(filename):
+            os.remove(filename)
+
+
+    def get_list_dir(mav_ftp, directory):
+        mav_ftp.cmd_list([directory])
+
+
+    def get_file(mav_ftp, remote_filename, local_filename, timeout=5):
+        logging_info("Will download %s to %s", remote_filename, local_filename)
+        mav_ftp.cmd_get([remote_filename, local_filename], timeout=timeout)
+
+
+    def get_last_log(mav_ftp):
+        try:
+            with open('LASTLOG.TXT', 'r', encoding='UTF-8') as file:
+                file_contents = file.readline()
+                remote_filenumber = int(file_contents.strip())
+        except FileNotFoundError:
+            logging_error("File LASTLOG.TXT not found.")
+            return
+        except ValueError:
+            logging_error("Could not extract last log file number from LASTLOG.TXT contants %s", file_contents)
+            return
+        remote_filenumber = remote_filenumber - 1 # we do not want the very last log
+        remote_filename = f'/APM/LOGS/{remote_filenumber:08}.BIN'
+        get_file(mav_ftp, remote_filename, 'LASTLOG.BIN', 0)
+        time.sleep(1) # wait for the file to be written to disk and for the FC to catch it's breath
+
+
+    def download_script(url, local_filename):
+        # Download the script from the internet to the PC
+        response = requests.get(url, timeout=5)
+
+        if response.status_code == 200:
+            with open(local_filename, "wb") as file:
+                file.write(response.content)
+        else:
+            logging_error("Failed to download the file")
+
+
+    def create_directory(mav_ftp, remote_directory):
+        mav_ftp.cmd_mkdir([remote_directory])
+
+
+    def upload_script(mav_ftp, remote_directory, local_filename, timeout):
+        # Upload it from the PC to the flight controller
+        mav_ftp.cmd_put([local_filename, remote_directory], timeout=timeout)
+        time.sleep(0.3) # wait for the FC to catch it's breath
+
+
+    def main():
+        '''for testing/example purposes only'''
+        args = argument_parser()
+
+        logging_basicConfig(level=logging_getLevelName(args.loglevel), format='%(asctime)s - %(levelname)s - %(message)s')
+
+        # create a mavlink serial instance
+        comport = auto_connect(args.device)
+        master = mavutil.mavlink_connection(comport.device, baud=args.baudrate, source_system=args.SOURCE_SYSTEM)
+
+        # wait for the heartbeat msg to find the system ID
+        wait_heartbeat(master)
+
+        mav_ftp = mavftp.MAVFTP(master,
+                                target_system=master.target_system,
+                                target_component=master.target_component)
+
+        delete_local_file_if_exists("params.param")
+        delete_local_file_if_exists("defaults.param")
+        mav_ftp.cmd_getparams(["params.param", "defaults.param"])
+
+        get_list_dir(mav_ftp, '/APM/LOGS/')
+
+        delete_local_file_if_exists("LASTLOG.TXT")
+        delete_local_file_if_exists("LASTLOG.BIN")
+        get_file(mav_ftp, '/APM/LOGS/LASTLOG.TXT', 'LASTLOG.TXT')
+
+        get_last_log(mav_ftp)
+
+        remote_directory = '/APM/Scripts/'
+        create_directory(mav_ftp, remote_directory)
+
+        url = "https://discuss.ardupilot.org/uploads/short-url/4pyrl7PcfqiMEaRItUhljuAqLSs.lua"
+        local_filename = "copter-magfit-helper.lua"
+
+        if not os.path.exists(local_filename):
+            download_script(url, local_filename)
+
+        upload_script(mav_ftp, remote_directory, local_filename, 5)
+
+        url = "https://raw.githubusercontent.com/ArduPilot/ardupilot/Copter-4.5/libraries/AP_Scripting/applets/VTOL-quicktune.lua"
+        local_filename = "VTOL-quicktune.lua"
+
+        if not os.path.exists(local_filename):
+            download_script(url, local_filename)
+
+        upload_script(mav_ftp, remote_directory, local_filename, 5)
+
+        master.close()
+
+
+    main()