tftpy doesn't load on Windows

[cmr-paul-rigas]

Commit 0039d8f introduced usage of the fcntl module to address #14, however the fcntl module doesn't exist on Windows so the tftpy module at version 0.8.6 won't load at all on Windows.

>>> import tftpy
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
  File "C:\dev\extern\venv\lib\site-packages\tftpy\__init__.py", line 13, in <module>
    from .TftpServer import TftpServer
  File "C:\dev\extern\venv\lib\site-packages\tftpy\TftpServer.py", line 16, in <module>
    from .TftpContexts import TftpContextServer
  File "C:\dev\extern\venv\lib\site-packages\tftpy\TftpContexts.py", line 18, in <module>
    import fcntl
ModuleNotFoundError: No module named 'fcntl'

[msoulier]

I would need to move to a locking abstraction. Maybe this one.

https://coderslegacy.com/python/lock-a-file-with-filelock/

[msoulier]

Or write my own and use https://docs.python.org/3/library/msvcrt.html

[msoulier]

I just pushed a commit that allows a tftp download on windows. I'm going to need to completely redo my test harness to be able to run it automatically on windows. I'm too reliant on fork(). And there's a lock somewhere in the server that is preventing the multiprocessing module from working. I haven't found it yet.

[cmr-paul-rigas]

I gave it a try building a wheel from master after your commit, but no data seems to be transferred (comparing output with 0.8.5).
Output snippet from 3f5132e

tftpy\TftpStates.py:569 Ack blocknumber is zero as expected
tftpy\TftpStates.py:570 Sending first DAT packet
tftpy\TftpStates.py:102 Read 0 bytes into buffer

Output snippet from 0.8.5

tftpy\TftpStates.py:569 Ack blocknumber is zero as expected
tftpy\TftpStates.py:570 Sending first DAT packet
tftpy\TftpStates.py:102 Read 71 bytes into buffer

[msoulier]

Hmm. I'll check again. I did a manual download on my sole windows box. Seemed to work but I'll look again.

[donbinford]

I sent an email to Michael as well but wanted to add a note here. In my test, if you replace the "fcntl" calls with "portalocker" calls it then allows my Windows setup to work again.

Here are the changes I made in TftpContexts.py. I have added them conditionally for Windows but I believe the conditional parts could be removed and just use "portalocker" since it works on Windows, Linux, Unix and BSD (cross platform).

https://github.com/WoLpH/portalocker

if os.name == "nt":
import portalocker
else:
import fcntl
:
:
if os.name == "nt":
portalocker.unlock(self.fileobj)
else:
fcntl.flock(self.fileobj, fcntl.LOCK_UN)
:
:
if os.name == "nt":
portalocker.lock(self.fileobj, portalocker.LOCK_SH | portalocker.LOCK_NB)
else:
fcntl.flock(self.fileobj, fcntl.LOCK_SH | fcntl.LOCK_NB)
:
:
if os.name == "nt":
portalocker.lock(self.fileobj, portalocker.LOCK_EX | portalocker.LOCK_NB)
else:
fcntl.flock(self.fileobj, fcntl.LOCK_EX | fcntl.LOCK_NB)

These changes work for my Windows needs.