Develop Reference

Trouble reading data from USB device using Python

I am using PyUSB library to read data from my USB mouse in windows. I was able to run the code in a UBUNTU virtual machine, but I can't replicate the same in windows. Can someone tell me what am I doing wrong? Following is the code and the error it throws :
import usb.core
import usb.util
# decimal vendor and product values
dev = usb.core.find(idVendor=1133, idProduct=49278)
if dev is None :
raise ValueError('Device is not found')
print(dev)
# first endpoint
interface = 0
endpoint = dev[0][(0,0)][0]
# if the OS kernel already claimed the device, which is most likely true
if dev.is_kernel_driver_active(interface) is True:
# tell the kernel to detach
dev.detach_kernel_driver(interface)
# claim the device
usb.util.claim_interface(dev, interface)
collected = 0
attempts = 50
while collected < attempts :
try:
data = dev.read(endpoint.bEndpointAddress,endpoint.wMaxPacketSize)
collected += 1
print(data)
except usb.core.USBError as e:
data = None
if e.args == ('Operation timed out',):
continue
# release the device
usb.util.release_interface(dev, interface)
# reattach the device to the OS kernel
dev.attach_kernel_driver(interface)
Traceback (most recent call last):
File "c:\BCD\i360\python\usb_reader.py", line 27, in <module>
if dev.is_kernel_driver_active(interface) is True:
File "C:\Python\Python38\lib\site-packages\usb\core.py", line 1107, in is_kernel_driver_active
self._ctx.managed_open()
File "C:\Python\Python38\lib\site-packages\usb\core.py", line 113, in wrapper
return f(self, *args, **kwargs)
File "C:\Python\Python38\lib\site-packages\usb\core.py", line 131, in managed_open
self.handle = self.backend.open_device(self.dev)
File "C:\Python\Python38\lib\site-packages\usb\backend\libusb1.py", line 804, in open_device
return _DeviceHandle(dev)
File "C:\Python\Python38\lib\site-packages\usb\backend\libusb1.py", line 652, in __init__
_check(_lib.libusb_open(self.devid, byref(self.handle)))
File "C:\Python\Python38\lib\site-packages\usb\backend\libusb1.py", line 600, in _check
raise NotImplementedError(_strerror(ret))
NotImplementedError: Operation not supported or unimplemented on this platform

The error says exactly what's wrong: You're using a function that makes no sense on your operating system (Windows).
So, don't do that? Either, if you know this is something only running on Windows, remove the check, or better, try:-handle the exception.

dev.is_kernel_driver_active(interface) is not supported in Windows

Most recent SFTP python package and best practices

I've been looking for SFTP python packages, ftpretty works fine for me:
https://pypi.org/project/ftpretty/
but I want to use a more secure protocol.
PySftp is obviously a bit outdated (Edit: it seems that pysftp is still frequently used, about the error please see below):
https://bitbucket.org/dundeemt/pysftp/src/master/
And throws me several errors on Win10, PyCharm, Python3.6:
C:\Users\bobin\PycharmProjects\classtest\venv\lib\site-packages\pysftp\__init__.py:61: UserWarning: Failed to load HostKeys from C:\Users\bobin\.ssh\known_hosts. You will need to explicitly load HostKeys (cnopts.hostkeys.load(filename)) or disableHostKey checking (cnopts.hostkeys = None).
warnings.warn(wmsg, UserWarning)
Traceback (most recent call last):
File "C:/Users/bobin/PycharmProjects/classtest/pysftptest.py", line 7, in <module>
with pysftp.Connection(host=myHostname, username=myUsername, password=myPassword) as sftp:
File "C:\Users\bobin\PycharmProjects\classtest\venv\lib\site-packages\pysftp\__init__.py", line 132, in __init__
self._tconnect['hostkey'] = self._cnopts.get_hostkey(host)
File "C:\Users\bobin\PycharmProjects\classtest\venv\lib\site-packages\pysftp\__init__.py", line 71, in get_hostkey
raise SSHException("No hostkey for host %s found." % host)
paramiko.ssh_exception.SSHException: No hostkey for host s233.goserver.host found.
Exception ignored in: <bound method Connection.__del__ of <pysftp.Connection object at 0x00000235B0695048>>
Traceback (most recent call last):
File "C:\Users\bobin\PycharmProjects\classtest\venv\lib\site-packages\pysftp\__init__.py", line 1013, in __del__
self.close()
File "C:\Users\bobin\PycharmProjects\classtest\venv\lib\site-packages\pysftp\__init__.py", line 784, in close
if self._sftp_live:
AttributeError: 'Connection' object has no attribute '_sftp_live'
Process finished with exit code 1
This thread seemed relevant to me but it's already 12years old:
SFTP in Python? (platform independent)
And the paramiko package is also throwing me errors:
Traceback (most recent call last):
File "C:\Users\bobin\PycharmProjects\classtest\venv\lib\site-packages\paramiko\sftp_client.py", line 130, in __init__
server_version = self._send_version()
File "C:\Users\bobin\PycharmProjects\classtest\venv\lib\site-packages\paramiko\sftp.py", line 134, in _send_version
t, data = self._read_packet()
File "C:\Users\bobin\PycharmProjects\classtest\venv\lib\site-packages\paramiko\sftp.py", line 201, in _read_packet
x = self._read_all(4)
File "C:\Users\bobin\PycharmProjects\classtest\venv\lib\site-packages\paramiko\sftp.py", line 188, in _read_all
raise EOFError()
EOFError
During handling of the above exception, another exception occurred:
Traceback (most recent call last):
File "C:/Users/bobin/PycharmProjects/classtest/paramikotest.py", line 12, in <module>
sftp = paramiko.SFTPClient.from_transport(transport)
File "C:\Users\bobin\PycharmProjects\classtest\venv\lib\site-packages\paramiko\sftp_client.py", line 170, in from_transport
return cls(chan)
File "C:\Users\bobin\PycharmProjects\classtest\venv\lib\site-packages\paramiko\sftp_client.py", line 132, in __init__
raise SSHException("EOF during negotiation")
paramiko.ssh_exception.SSHException: EOF during negotiation
Process finished with exit code 1
I have come so far to understand that I probably need a keyfile that I can find out by first connecting to my webspace using e.g. filezilla:
How To Extract SFTP SSH Key From Key Cache in FileZilla FTP Client
My question is: how do I establish an SFTP connection to my host, which is webgo: https://www.webgo.de/hilfe/content/76/52/de/was-ist-sftp.html
EDIT: providing no host_key as follows:
import pysftp
cnopts = pysftp.CnOpts()
cnopts.hostkeys = None
myHostname = "host"
myUsername = "user"
myPassword = "pass"
with pysftp.Connection(host=myHostname, username=myUsername, password=myPassword, cnopts=cnopts, port=22) as sftp:
print("Connection succesfully stablished ... ")
sftp.put('C:\TEMP\Capture.PNG', preserve_mtime=True)
still throws me an error for providing no host_keys:
C:\Users\bobin\PycharmProjects\classtest\venv\lib\site-packages\pysftp\__init__.py:61: UserWarning: Failed to load HostKeys from C:\Users\bobin\.ssh\known_hosts. You will need to explicitly load HostKeys (cnopts.hostkeys.load(filename)) or disableHostKey checking (cnopts.hostkeys = None).
warnings.warn(wmsg, UserWarning)
EDIT2: tried prettyftp but my provider is refusing the connection:
Traceback (most recent call last):
File "C:/Users/bobin/PycharmProjects/classtest/testftp.py", line 15, in <module>
f.put('C:\TEMP\Capture.PNG', 'Capture230.PNG')
File "C:\Users\bobin\PycharmProjects\classtest\venv\lib\site-packages\ftpretty.py", line 119, in put
self.conn.storbinary('STOR %s' % remote_file, local_file)
File "C:\Users\bobin\AppData\Local\Programs\Python\Python36\lib\ftplib.py", line 513, in storbinary
return self.voidresp()
File "C:\Users\bobin\AppData\Local\Programs\Python\Python36\lib\ftplib.py", line 249, in voidresp
resp = self.getresp()
File "C:\Users\bobin\AppData\Local\Programs\Python\Python36\lib\ftplib.py", line 242, in getresp
raise error_temp(resp)
ftplib.error_temp: 425 Unable to build data connection: Operation not permitted
Used following code snippet, setting secure=False worked again:
from ftpretty import ftpretty
# Minimal
f = ftpretty('host','user','pass', port=21, secure=True)
f.put('C:\TEMP\Capture.PNG', 'Capture230.PNG')
f.close()

For the first error, it seems like a bug in pysftp.
You can have a look at the Connection class here on line 76, and the attribute _sftp_live is defined on line 134, so this is definitely an error occurring at runtime without being validated correctly. I have also been able to find this related error, which likely explains the cause of this issue; the solution is also mentioned in the error if you want to explicitly fix it.
I would still consider using ftpretty. It does use TLS for security and a pretty safe wrapper, you can simply enable it by setting the secure parameter to True (secure=True) - which by default is set as False.

Using VS Code to debug python files. Exception thrown on breakpoint and breakpoint is ignored

Tried with multiple different python files. Every time I try to use the debugger in vs code and set breakpoints the breakpoint gets ignored and exception gets raised and the script continues on. I've been googling and tinkering for over 2 hours and can't seem to figure out what's going on here. Tried rebooting PC, running vs code as admin, uninstall/reinstall the python extension for vs code. Tried to dig into the files mentioned in the traceback and pinpointed the function that seems to be raising the exception but I can't figure out where it's being called from or why it's raising the exception. I'm still new-ish to Python. Debugging works properly on my laptop but for whatever reason my desktop is having this issue.
Traceback (most recent call last):
File "c:\Users\Joel\.vscode\extensions\ms-python.python-2020.7.96456\pythonFiles\lib\python\debugpy\_vendored\pydevd\pydevd_file_utils.py", line 529, in _original_file_to_client
return cache[filename]
KeyError: 'c:\\users\\joel\\local settings\\application data\\programs\\python\\python37-32\\lib\\runpy.py'
During handling of the above exception, another exception occurred:
Traceback (most recent call last):
File "c:\Users\Joel\.vscode\extensions\ms-python.python-2020.7.96456\pythonFiles\lib\python\debugpy\_vendored\pydevd\_pydevd_bundle\pydevd_comm.py", line 330, in _on_run
self.process_net_command_json(self.py_db, json_contents)
File "c:\Users\Joel\.vscode\extensions\ms-python.python-2020.7.96456\pythonFiles\lib\python\debugpy\_vendored\pydevd\_pydevd_bundle\pydevd_process_net_command_json.py", line 190, in process_net_command_json
cmd = on_request(py_db, request)
File "c:\Users\Joel\.vscode\extensions\ms-python.python-2020.7.96456\pythonFiles\lib\python\debugpy\_vendored\pydevd\_pydevd_bundle\pydevd_process_net_command_json.py", line 771, in on_stacktrace_request
self.api.request_stack(py_db, request.seq, thread_id, fmt=fmt, start_frame=start_frame, levels=levels)
File "c:\Users\Joel\.vscode\extensions\ms-python.python-2020.7.96456\pythonFiles\lib\python\debugpy\_vendored\pydevd\_pydevd_bundle\pydevd_api.py", line 214, in request_stack
if internal_get_thread_stack.can_be_executed_by(get_current_thread_id(threading.current_thread())):
File "c:\Users\Joel\.vscode\extensions\ms-python.python-2020.7.96456\pythonFiles\lib\python\debugpy\_vendored\pydevd\_pydevd_bundle\pydevd_comm.py", line 661, in can_be_executed_by
py_db, self.seq, self.thread_id, frame, self._fmt, must_be_suspended=not timed_out, start_frame=self._start_frame, levels=self._levels)
File "c:\Users\Joel\.vscode\extensions\ms-python.python-2020.7.96456\pythonFiles\lib\python\debugpy\_vendored\pydevd\_pydevd_bundle\pydevd_net_command_factory_json.py", line 213, in make_get_thread_stack_message
py_db, frames_list
File "c:\Users\Joel\.vscode\extensions\ms-python.python-2020.7.96456\pythonFiles\lib\python\debugpy\_vendored\pydevd\_pydevd_bundle\pydevd_net_command_factory_xml.py", line 175, in _iter_visible_frames_info
new_filename_in_utf8, applied_mapping = pydevd_file_utils.norm_file_to_client(filename_in_utf8)
File "c:\Users\Joel\.vscode\extensions\ms-python.python-2020.7.96456\pythonFiles\lib\python\debugpy\_vendored\pydevd\pydevd_file_utils.py", line 531, in _original_file_to_client
translated = _path_to_expected_str(get_path_with_real_case(_AbsFile(filename)))
File "c:\Users\Joel\.vscode\extensions\ms-python.python-2020.7.96456\pythonFiles\lib\python\debugpy\_vendored\pydevd\pydevd_file_utils.py", line 221, in _get_path_with_real_case
return _resolve_listing(drive, iter(parts))
File "c:\Users\Joel\.vscode\extensions\ms-python.python-2020.7.96456\pythonFiles\lib\python\debugpy\_vendored\pydevd\pydevd_file_utils.py", line 184, in _resolve_listing
dir_contents = cache[resolved_lower] = os.listdir(resolved)
PermissionError: [WinError 5] Access is denied: 'C:\\Users\\Joel\\Local Settings'
So I get this traceback every time a breakpoint is hit. Taking a peek at the "_original_file_to_client" function in "pydevd_file_utils.py" we get this:
def _original_file_to_client(filename, cache={}):
try:
return cache[filename]
except KeyError:
translated = _path_to_expected_str(get_path_with_real_case(_AbsFile(filename)))
cache[filename] = (translated, False)
return cache[filename]
I wasn't able to figure out where this function was being called from or what the expected output was supposed to be. Any help with this would be greatly appreciated!
Edit: Forgot to mention I'm using Windows 10 if it wasn't obvious from the trace

This is a similar question. The spaces in the filename cause this problem:
"Local Settings", "application data"

python: win32com.client.GetActiveObject("iTunes.Application") failing

I've been launching itunes with
try:
itapp= win32com.client.Dispatch('iTunes.Application')
except:
itapp= win32com.client.GetActiveObject('iTunes.Application')
Today, whenever I run this, if itunes is already running, it fails with
Traceback (most recent call last):
File "fix_m4a.py", line 63, in <module>
change_itunes_path(s,d)
File "fix_m4a.py", line 45, in change_itunes_path
itapp = win32com.client.GetActiveObject('iTunes.Application')
File "C:\program files\python27\lib\site-packages\win32com\client\__init__.py"
, line 79, in GetActiveObject
dispatch = pythoncom.GetActiveObject(resultCLSID)
pywintypes.com_error: (-2147221021, 'Operation unavailable', None, None)
Works fine if itunes is not running
The only recent change I've made is going from 2.7.5 to 2.7.6.
Why is this failing?

Try using the comtypes Python package - it has better support for custom COM objects.
Instead of
try:
itapp= win32com.client.Dispatch('iTunes.Application')
except:
itapp= win32com.client.GetActiveObject('iTunes.Application')
Try this:
from comtypes.client import CreateObject, GetActiveObject
try:
itapp = CreateObject('iTunes.Application')
except:
itapp = GetActiveObject('iTunes.Application')
comtypes: http://sourceforge.net/projects/comtypes/

Errors when connecting to router with python code

I am trying to connect to some router using the above code and I am using juniperj2320.py module and in test file I have
am using code base from this http://subversion.assembla.com/svn/clauzsistel08/trunk/dist/
#!/usr/bin/python
from localconf import *
from juniperj2320 import *
import sys
import traceback
SERIALDEVICE = '/dev/ttyUSB0'
# Now configure the router
try:
router = JuniperJ2320(SERIALDEVICE)
except RouterConfigurationException, err:
print "Router configuration error: ", err
print "Please try again."
sys.exit(1)
but am getting this following error
./test.py
> /root/pyserial-2.6/examples/serialrouter.py(37)__init__()
-> serial.Serial.__init__(self, serialdevice, baudrate=baudrate, \
(Pdb) c
Traceback (most recent call last):
File "./test.py", line 30, in
router = JuniperJ2320(SERIALDEVICE)
File "/root/pyserial-2.6/examples/juniperj2320.py", line 32, in __init__
BYTESIZE, PARITY, STOPBITS, TIMEOUT)
File "/root/pyserial-2.6/examples/serialrouter.py", line 44, in __init__
fdpexpect.fdspawn.__init__(self, self.fileno())
File "/usr/lib/python2.6/site-packages/fdpexpect.py", line 40, in __init__
spawn.__init__(self, None, args, timeout, maxread, searchwindowsize, logfile )
File "/usr/lib/python2.6/site-packages/pexpect.py", line 412, in __init__
self.closed = True # File-like object.
AttributeError: can't set attribute
and absolutely clue less on wat happening here ! any help ll be greatly appreciated
thanks

This is a little bit of a shot in the dark, because I'm not familiar with the modules you're using, but based on the traceback, it looks like the constructor is expecting a file-like object, not just a file path. Try this instead.
SERIALDEVICE = '/dev/ttyUSB0'
# Now configure the router
try:
router = JuniperJ2320(open(SERIALDEVICE))

Instead of writing your own serial communications program wouldn't be easier to have pexpect drive a serial program like minicom?