[New-bugs-announce] [issue32331] apply SOCK_TYPE_MASK to socket.type on Linux
report at bugs.python.org
Thu Dec 14 22:42:49 EST 2017
New submission from Yury Selivanov <yselivanov at gmail.com>:
On Linux, socket type is both a socket type and a bit mask (of SOCK_CLOEXEC and SOCK_NONBLOCK). Therefore, anyone who write code like 'if sock.type == SOCK_STREAM' writes non-portable code, that occasionally breaks on Linux.
This caused some hard to spot bugs in asyncio already: https://bugs.python.org/issue27456 -- this one was discovered only 1 year after the actual change.
On Linux, in 'include/linux/net.h' there's a SOCK_TYPE_MASK macro defined to 0xF. The idea is that on Linux you should mask socket type before comparing it to SOCK_STREAM or other socket types.
Using socket.SOCK_NONBLOCK on Python was always error-prone even if one targets only Linux. For instance, socket.type won't be updated to include SOCK_NONBLOCK if the socket was updated via ioctl call directly.
Therefore, I propose to fix socket.type getter to always (on Linux) apply that mask in Python.
components: Library (Lib)
nosy: asvetlov, inada.naoki, pitrou, vstinner, yselivanov
title: apply SOCK_TYPE_MASK to socket.type on Linux
versions: Python 3.7
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