[Python-Dev] PEP 446: cloexec flag on os.open

[Ronald Oussoren]

Victor,

PEP 446 mentions that a cloexec flag gets added to os.open. This API already has a way to specify this: the O_CLOEXEC bit in the flags argument. A new cloexec parameter is nicely consistent with the other APIs, but introcudes a second way to set that flag.

What will the following calls do?:

    os.open(path, os.O_RDONLY|os.O_CLOEXEC, cloexec=False)
    os.open(path, os.O_RDONLY, cloexec=True)

The PEP doesn't specify this, but the implementation for PEP 443 in issue 17036 basicly ignores the cloexec argument in the first call and adds O_CLOEXEC in the second call. That can lead to confusing behavior when the flags argument to os.open is passed from elsewhere (e.g. a wrapper around os.open that passes in arguments and just overrides the cloexec argument).

It might be better to just drop the cloexec flag to os.open and make os.O_CLOEXEC an alias for os.O_NOINHERIT on Windows.

Ronald