Thanks, Victor. I don't have any experience with dir_fd handling, so unfortunately can't really comment here.
What advantages does it bring? I notice that even os.listdir() on Python 3.4 doesn't have anything related to file descriptors, so I'd be in favour of not including support. We can always add it later. -Ben On Tue, Jul 1, 2014 at 3:44 AM, Victor Stinner <victor.stin...@gmail.com> wrote: > Hi, > > IMO we must decide if scandir() must support or not file descriptor. > It's an important decision which has an important impact on the API. > > > To support scandir(fd), the minimum is to store dir_fd in DirEntry: > dir_fd would be None for scandir(str). > > > scandir(fd) must not close the file descriptor, it should be done by > the caller. Handling the lifetime of the file descriptor is a > difficult problem, it's better to let the user decide how to handle > it. > > There is the problem of the limit of open file descriptors, usually > 1024 but it can be lower. It *can* be an issue for very deep file > hierarchy. > > If we choose to support scandir(fd), it's probably safer to not use > scandir(fd) by default in os.walk() (use scandir(str) instead), wait > until the feature is well tested, corner cases are well known, etc. > > > The second step is to enhance pathlib.Path to support an optional file > descriptor. Path already has methods on filenames like chmod(), > exists(), rename(), etc. > > > Example: > > fd = os.open(path, os.O_DIRECTORY) > try: > for entry in os.scandir(fd): > # ... use entry to benefit of entry cache: is_dir(), lstat_result ... > path = pathlib.Path(entry.name, dir_fd=entry.dir_fd) > # ... use path which uses dir_fd ... > finally: > os.close(fd) > > Problem: if the path object is stored somewhere and use after the > loop, Path methods will fail because dir_fd was closed. It's even > worse if a new directory uses the same file descriptor :-/ (security > issue, or at least tricky bugs!) > > Victor > _______________________________________________ > Python-Dev mailing list > Python-Dev@python.org > https://mail.python.org/mailman/listinfo/python-dev > Unsubscribe: > https://mail.python.org/mailman/options/python-dev/benhoyt%40gmail.com _______________________________________________ Python-Dev mailing list Python-Dev@python.org https://mail.python.org/mailman/listinfo/python-dev Unsubscribe: https://mail.python.org/mailman/options/python-dev/archive%40mail-archive.com
