Use Linux' O_TMPFILE for tmpfiles

[untitaker]

https://github.com/untitaker/rust-atomicwrites/issues/2

[untitaker]

Unsure how to call linkat in Python.

[AndCycle]

https://docs.python.org/3/library/os.html#os.O_TMPFILE

[jwilk]

Something like this seems to work since Python 3.4:

import os
fd = os.open('.', os.O_TMPFILE | os.O_RDWR)
path = '/proc/self/fd/{0}'.format(fd)
os.link(path, 'spam', src_dir_fd=0, follow_symlinks=True)

[untitaker]

@jwilk That doesn't seem particularly performant or elegant though. It seems that there is a package on PyPI that provides bindings for this call, however, that would be quite a microdependency.

[earonesty]

AFAICT NamedTemporaryFile already sets this flag

[jwilk]

I think you meant (unnamed) TemporaryFile, which indeed tries to use O_TMPFILE since Python 3.5: https://bugs.python.org/issue21515