[New-bugs-announce] [issue21719] Returning Windows file attribute information via os.stat()

[Ben Hoyt]

New submission from Ben Hoyt:

I asked recently on python-dev [1] about adding a "st_winattrs" attribute to stat result objects on Windows, to return the full set of Windows file attribute bits, such as "hidden" or "compressed" status. Copying from that thread for a bit more context here:

Python's os.stat() simply discards most of the file attribute
information fetched via the Win32 system calls. On Windows, os.stat()
calls CreateFile to open the file and get the dwFileAttributes value,
but it throws it all away except the FILE_ATTRIBUTE_DIRECTORY and
FILE_ATTRIBUTE_READONLY bits. See CPython source at [2].

Given that os.stat() returns extended, platform-specific file
attributes on Linux and OS X platforms (for example,
st_blocks, st_rsize, etc), it seems that Windows is something of a
second-class citizen here.

There are several questions on StackOverflow about how to get this
information on Windows, and one has to resort to ctypes. For example,
[3].

To solve this problem, I think we should add a "st_winattrs" attribute to the object returned by os.stat() on
Windows. And we should add the relevant Win32 FILE_ATTRIBUTE_* constants to the "stat" module.

Then, similarly to existing code like hasattr(st, 'st_blocks') on
Linux, you could write a cross-platform function to determine if a
file was hidden, something like so:

    def is_hidden(path):
        if startswith(os.path.basename(path), '.'):
            return True
        st = os.stat(path)
        return getattr(st, 'st_winattrs', 0) & FILE_ATTRIBUTE_HIDDEN != 0

There was general support for this idea on python-dev (see [4] [5] [6]), so I'd love to see this in Python 3.5.

Basically we need to add a "st_winattrs" integer attribute to the win32_stat struct in posixmodule.c and add the FILE_ATTRIBUTE_* constants to _stat.c, as well as adding Windows-specific tests and documentation.

I've never compiled CPython on Windows, but I aim to provide a patch for this at some stage soonish. Feedback and other patches welcome in the meantime. :-)

[1] https://mail.python.org/pipermail/python-dev/2014-June/134990.html
[2] https://github.com/python/cpython/blob/master/Modules/posixmodule.c#L1462
[3] http://stackoverflow.com/a/6365265
[4] https://mail.python.org/pipermail/python-dev/2014-June/134993.html
[5] https://mail.python.org/pipermail/python-dev/2014-June/135006.html
[6] https://mail.python.org/pipermail/python-dev/2014-June/135007.html

----------
components: Library (Lib)
messages: 220266
nosy: benhoyt, ethan.furman, zach.ware
priority: normal
severity: normal
status: open
title: Returning Windows file attribute information via os.stat()
type: enhancement
versions: Python 3.5

_______________________________________
Python tracker <report at bugs.python.org>
<http://bugs.python.org/issue21719>
_______________________________________