[Python-Dev] PEP 446: Open issues/questions

[Charles-François Natali]

2013/7/28 Antoine Pitrou <solipsis at pitrou.net>:
>> (C) Should we handle standard streams (0: stdin, 1: stdout, 2: stderr)
>> differently? For example, os.dup2(fd, 0) should make the file
>> descriptor 0 (stdin) inheritable or non-inheritable? On Windows,
>> os.set_inheritable(fd, False) fails (error 87, invalid argument) on
>> standard streams (0, 1, 2) and copies of the standard streams (created
>> by os.dup()).
>
> I have been advocating for that, but I now realize that special-casing
> these three descriptors in a myriad of fd-creating functions isn't very
> attractive.
> (if a standard stream fd has been closed, any fd-creating function can
> re-create that fd: including socket.socket(), etc.)
>
> So perhaps only the *original* standard streams should be left
> inheritable?

Having stdin/stdout/stderr cloexec (e.g. after a dup() to redirect to
a log file, a socket...) will likely break a lot of code, e.g. code
using os.system(), or code calling exec manually (and I'm sure there's
a bunch of it).

Also, it'll be puzzling to have syscalls automatically set the cloexec
flag. I guess a lot of people doing system programming with Python
will get bitten, but that's a discussion we already had months ago...

cf