[Listing a MacOS Shared folder] smbclient.walk Generator raises StopIteration when encountering symbolic link

[loys-bkube]

Hello,

Firstly, let me thank you for this amazing project, it makes SMB communication a breeze in python.
I am sorry for my approximative english, it is indeed not my first language.

I am using your package to smbclient.walk through the full tree of a folder shared by a MacOS Sequoia 15.4.1

It works for all my cases but I have a folder where a symlink can be found.

When walk hits the symbolic link, with or without follow_symlinks=True it raises "Runtime Error : Generator raised StopIteration."

But the walk is not complete, the filesystem hasn't been fully iterated through.

Is this normal and expected ?

If it is, how should I walk through a folder using the smbclient.walk function ?

I did a few tests and it seems that :

• Whether the symlink points outside the targeted root doesn't matter.
• The folder I'm iterating through can be fully walked if there are no symlinks inside.
• Tested to walk this folder with the client on a Linux machine AND a Windows, both experience the same issue
• The error appears also when providing an "onerror" function

I did not test to host the shared folder on another operating system than MacOS 15.4.1.

Below is a reproducting snippet

⚠️ Make sure the folder you're walking through has a subfolder with a symlink inside.

I created mine with ln -s target.txt mylink

import smbclient

def onerror(e):
    print("Error occured", e)

def test_smb():
    try:
        smbclient.register_session("192.168.20.15", username="test", password="****")
        for root, _, files in smbclient.walk("\\\\192.168.20.15\\Bureau\\DossierABkp", topdown=True, onerror=onerror):
            print(root)
            
    except Exception as e:
        print("Une erreur de listing", e)
        # print("Authentication info ", ip, user, password, current_path)
        return []
        
test_smb()

Thank you for your time and this cool project.

[jborean93]

Thanks for the reproducer I'll have to try it out and see what exactly happens internally. The StopIteration shouldn't be exposed publicly here. Symlinks are weird in SMB where there is a builtin mechanism to expose the target but how they are implemented are server specific and is also affected by whether the target points to something inside the share or outside.

[jborean93]

Ok I've figured out what the issue is, on the macOS server when trying to find the symlink information it returns a STATUS_STOPPED_ON_SYMLINK but unlike Windows it doesn't return the buffer containing the symlink target. This has the reparse_buffer next() iterator fail with the StopIteration because there is no buffer

smbprotocol/src/smbprotocol/connection.py

Line 1058 in 5e56171

reparse_buffer = next(e for e in exp.error_details if isinstance(e, SMB2SymbolicLinkErrorResponse))

We can certainly handle this better but we won't be able to determine whether the symlink is pointing to a file or directory if the SMB server doesn't give us the target.

[jborean93]

I've opened a PR which handles this error and also to treat such symlink response as effectively a symlink with a broken target #334. While technically we could do more to try and manually get the reparse data buffer I don't think it is worth the extra complexity to do so here.