Function fwalk

Lib/os.py:452–497

Directory tree generator. This behaves exactly like walk(), except that it yields a 4-tuple dirpath, dirnames, filenames, dirfd `dirpath`, `dirnames` and `filenames` are identical to walk() output, and `dirfd` is a file descriptor referring to the directory `di

(top=".", topdown=True, onerror=None, *, follow_symlinks=False, dir_fd=None)

if {open, stat} <= supports_dir_fd and {scandir, stat} <= supports_fd:

    def fwalk(top=".", topdown=True, onerror=None, *, follow_symlinks=False, dir_fd=None):
        """Directory tree generator.

        This behaves exactly like walk(), except that it yields a 4-tuple

            dirpath, dirnames, filenames, dirfd

        `dirpath`, `dirnames` and `filenames` are identical to walk() output,
        and `dirfd` is a file descriptor referring to the directory `dirpath`.

        The advantage of fwalk() over walk() is that it&#x27;s safe against symlink
        races (when follow_symlinks is False).

        If dir_fd is not None, it should be a file descriptor open to a directory,
          and top should be relative; top will then be relative to that directory.
          (dir_fd is always supported for fwalk.)

        Caution:
        Since fwalk() yields file descriptors, those are only valid until the
        next iteration step, so you should dup() them if you want to keep them
        for a longer period.

        Example:

        import os
        for root, dirs, files, rootfd in os.fwalk('python/Lib/xml'):
            print(root, "consumes", end="")
            print(sum(os.stat(name, dir_fd=rootfd).st_size for name in files),
                  end="")
            print("bytes in", len(files), "non-directory files")
            if '__pycache__' in dirs:
                dirs.remove('__pycache__')  # don't visit __pycache__ directories
        """
        sys.audit("os.fwalk", top, topdown, onerror, follow_symlinks, dir_fd)
        top = fspath(top)
        stack = [(_fwalk_walk, (True, dir_fd, top, top, None))]
        isbytes = isinstance(top, bytes)
        try:
            while stack:
                yield from _fwalk(stack, isbytes, topdown, onerror, follow_symlinks)
        finally:
            # Close any file descriptors still on the stack.
            while stack:
                action, value = stack.pop()
                if action == _fwalk_close:
                    close(value)

    # Each item in the _fwalk() stack is a pair (action, args).
    _fwalk_walk = 0  # args: (isroot, dirfd, toppath, topname, entry)