path fd resolution

path.py

#!/usr/bin/python3
import contextlib
import os


def find_entry(dir_fd: int, target) -> os.DirEntry:

    with os.scandir(dir_fd) as it:
        for entry in it:
            info = entry.stat(follow_symlinks=False)

            if os.path.samestat(target, info):
                return entry

    return None


@contextlib.contextmanager
def close_fd_on_error(fd: int):
    try:
        yield
    except:
        os.close(fd)
        raise


def path_for_fd(target: int) -> str:
    flags = os.O_RDONLY | os.O_CLOEXEC | os.O_NOFOLLOW | os.O_DIRECTORY

    root_info = os.stat("/")

    parent = os.open("..", flags, dir_fd=target)
    result = []

    while True:

        with close_fd_on_error(parent):

            # Check if we have reached root
            info = os.fstat(target)
            if os.path.samestat(root_info, info):
                break

            entry = find_entry(parent, info)

            if entry is None:
                raise FileNotFoundError(f"Could not find entry {str(result)}")

            print(entry)

        result.append(entry.name)

        with close_fd_on_error(parent):
            target = parent
            parent = os.open("..", flags, dir_fd=parent)

    return "/" + "/".join(reversed(result))