Enable Direct Browsing of LittleFS Storage Device on Windows

[Jiajun-Huang]

This is an excellent Python interface for LittleFS; however, there is currently no support for users to directly browse the storage device with LittleFS on Windows. This pull request aims to address this by introducing support for browsing through the storage device. This is achieved by implementing a new UserContext with a device/file path arrangement.

Testing has only been conducted manually using an SD card adapter and USB flash.

A small sample code to show how it works.

disk_path = r"\\.\F: " # assume F drive is your storage device for littlefs
fs = LittleFS(block_size=512, block_count=30228480, mount=False, context=UserContextWinDisk(disk_path))
fs.mount()
print(fs.listdir('/'))
with fs.open('deadbeef.txt', 'rb') as fh:
    data = fh.read()

[BrianPugh]

try to avoid large try/excepts, as you could catch unintended exceptions. I would:

import ctypes
try:
    import win32file
except ImportError:
    pass
else:
    # Put the UserContextWinDisk implementation here.

[Jiajun-Huang]

This is what I want to do! Didn't know I could do that. Also, instead of pass, I think it might be better to add a message to warn the user.

[BrianPugh]

I think a OSError or IOError might be more appropriate.

[BrianPugh]

so hold on, this now makes win32file a hard requirement. We should only raise an error if the user attempts to instantiate UserContextWinDisk. The following is probably closer to what we want:

try:
    import win32file
except ImportError:
    win32file = None

class UserContextWinDisk(UserContext):
     def __init__(self, disk_path:str) -> None:
         if win32file is None:
             raise ImportError(...)
         # rest of WinDisk implementation

[BrianPugh]

so sorry, with this new implementation (checking win32file in __init__), then we no longer need this else:

try:  
     import win32file  
 except ImportError:
     win32file = None
 
class UserContextWinDisk(UserContext):
    ...

Otherwise right now we get ImportErrors if win32file is not available.

[BrianPugh]

looks great to me! thank you!