[Python-Dev] Add "e" (close and exec) mode to open()

[Gregory P. Smith]

On Mon, Jan 7, 2013 at 4:03 PM, Benjamin Peterson <benjamin at python.org>wrote:

> 2013/1/7 Victor Stinner <victor.stinner at gmail.com>:
> > Hi,
> >
> > I would like add a new flag to open() mode to close the file on exec:
> > "e". This feature exists using different APIs depending on the OS and
> > OS version: O_CLOEXEC, FD_CLOEXEC and O_NOINHERIT. Do you consider
> > that such flag would be interesting?
>
> I'm not sure it's worth cluttering the open() interface with such a
> non-portable option. People requiring such control should use the
> low-level os.open interface.
>

The ability to supply such flags really belongs on _all_ high or low level
file descriptor creating APIs so that things like subprocess_cloexec_pipe()
would not be necessary:
http://hg.python.org/cpython/file/0afa7b323abb/Modules/_posixsubprocess.c#l729

I'm not excited about raising an exception when it isn't supported; it
should attempt to get the same behavior via multiple API calls instead
(thus introducing a race condition for threads+fork+exec, but there is no
choice at that point and it is what most people would want in that
situation regardless). Not being supported will be such an extremely rare
situation for any OS someone runs a Python 3.4 program on that that detail
is pretty much a non-issue either way as far as I'm concerned.

-gps
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