Python os.walk() alternative that treats windows junctions as symlinks and will not iterate into them.

winwalk.py

import os
import stat

def is_reparse_point(path: str) -> bool:
    """
    Return True if the given path is a Windows reparse point (junction, symlink, mount point, etc.).
    On non-Windows, just use os.path.islink.
    """
    try:
        st = os.lstat(path)
    except OSError:
        return False

    # On Windows, check reparse attribute
    if hasattr(st, "st_file_attributes"):
        return bool(st.st_file_attributes & stat.FILE_ATTRIBUTE_REPARSE_POINT)

    # On POSIX, treat symlinks as "reparse points"
    return os.path.islink(path)

def winwalk(top, topdown=True, onerror=None, followlinks=False):
    """
    os.walk replacement for Windows that does not recurse into reparse points.

    Windows has the concept of junctions, which are similar to symlinks but
    are implemented differently. The built-in os.walk with followlinks=True
    will recurse into junctions, which can lead to infinite recursion if
    there are circular references. This function avoids that by checking for
    reparse points and not recursing into them.

    This function yields a 3-tuple (dirpath, dirnames, filenames) just like os.walk.

    Parameters:
    - top: The root directory to start walking from.
    - topdown: If True, the directories are generated from the top down.
    - onerror: A function that gets called with an OSError instance if an error occurs
        while listing directories.
    - followlinks: If True, symbolic links are followed. This is passed to os.walk
        when followlinks is True, but reparse points are still not recursed into.

    Example usage:
        for dirpath, dirnames, filenames in winwalk('C:\\mydir'):
            print(dirpath, dirnames, filenames)
    """
    if followlinks:
        return os.walk(top, topdown=topdown, onerror=onerror)

    try:
        names = os.listdir(top)
    except OSError as err:
        if onerror is not None:
            onerror(err)
        return

    dirs, nondirs = [], []
    for name in names:
        fullpath = os.path.join(top, name)
        try:
            if os.path.isdir(fullpath) and not is_reparse_point(fullpath):
                dirs.append(name)
            else:
                nondirs.append(name)
        except OSError:
            nondirs.append(name)

    if topdown:
        yield top, dirs, nondirs

    for d in dirs:
        new_path = os.path.join(top, d)
        yield from winwalk(new_path, topdown, onerror)

    if not topdown:
        yield top, dirs, nondirs