_XOPEN_SOURCE and _XOPEN_SOURCE_EXTENDED usage on Solaris

[neologix]

BPO	12999
Nosy	@loewis, @jcea, @vstinner, @tiran

^{Note: these values reflect the state of the issue at the time it was migrated and might not reflect the current state.}

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GitHub fields:

assignee = None
closed_at = <Date 2013-08-02.08:59:35.110>
created_at = <Date 2011-09-17.07:17:25.266>
labels = ['type-bug']
title = '_XOPEN_SOURCE and _XOPEN_SOURCE_EXTENDED usage on Solaris'
updated_at = <Date 2013-08-02.08:59:35.109>
user = 'https://bugs.python.org/neologix'

bugs.python.org fields:

activity = <Date 2013-08-02.08:59:35.109>
actor = 'neologix'
assignee = 'none'
closed = True
closed_date = <Date 2013-08-02.08:59:35.110>
closer = 'neologix'
components = []
creation = <Date 2011-09-17.07:17:25.266>
creator = 'neologix'
dependencies = []
files = []
hgrepos = []
issue_num = 12999
keywords = []
message_count = 6.0
messages = ['144175', '144184', '144185', '144235', '192673', '194167']
nosy_count = 5.0
nosy_names = ['loewis', 'jcea', 'vstinner', 'christian.heimes', 'neologix']
pr_nums = []
priority = 'normal'
resolution = 'fixed'
stage = 'needs patch'
status = 'closed'
superseder = None
type = 'behavior'
url = 'https://bugs.python.org/issue12999'
versions = ['Python 3.3']

[neologix]

While testing issue python/cpython#57190, I stumbled on a problem on OpenIndiana buildbot:
"""
test test_multiprocessing crashed -- Traceback (most recent call last):
  File "/export/home/buildbot/64bits/custom.cea-indiana-amd64/build/Lib/test/regrtest.py", line 1133, in runtest_inner
    the_package = __import__(abstest, globals(), locals(), [])
  File "/export/home/buildbot/64bits/custom.cea-indiana-amd64/build/Lib/test/test_multiprocessing.py", line 38, in <module>
    from multiprocessing import util, reduction
  File "/export/home/buildbot/64bits/custom.cea-indiana-amd64/build/Lib/importlib/_bootstrap.py", line 437, in load_module
    return self._load_module(fullname)
  File "/export/home/buildbot/64bits/custom.cea-indiana-amd64/build/Lib/importlib/_bootstrap.py", line 141, in decorated
    return fxn(self, module, *args, **kwargs)
  File "/export/home/buildbot/64bits/custom.cea-indiana-amd64/build/Lib/importlib/_bootstrap.py", line 342, in _load_module
    exec(code_object, module.__dict__)
  File "/export/home/buildbot/64bits/custom.cea-indiana-amd64/build/Lib/multiprocessing/reduction.py", line 57, in <module>
    raise ImportError('pickling of connections not supported')
ImportError: pickling of connections not supported
"""

Which means that socket.CMSG_LEN isn't defined.
Now, you might wonder how this can work in the C version of multiprocessing.(sendfd|recvfd), which needs CMSG_LEN().
Here's how:
"""
#ifdef __sun
 /* The control message API is only available on Solaris      
    if XPG 4.2 or later is requested. */      
 #define _XOPEN_SOURCE 500     
 #endif
"""

And indeed:
http://fxr.watson.org/fxr/source/common/sys/socket.h?v=OPENSOLARIS#L478
"""
#if defined(_XPG4_2)
/*
 * The cmsg headers (and macros dealing with them) were made available as
 * part of UNIX95 and hence need to be protected with a _XPG4_2 define.
 */
"""

The problem is that socketmodule uses pyconfig.h defines, and _XOPEN_SOURCE isn't defined on Solaris:
http://hg.python.org/cpython/rev/7c947768b435

(it was added explicitely to Modules/_multiprocessing/multiprocessing.h for sendmsg by http://hg.python.org/cpython/rev/419901e65dd2).
So, _XOPEN_SOURCE is needed on Solaris to build socket_sendmsg and friends.
I'm not sure about the best way to proceed, since Martin certainly had good reasons to remove _XOPEN_SOURCE definition entirely on Solaris.
Should we define it only at the top of socketmodule?

[jcea]

See too http://bugs.python.org/issue6755#msg143798

[jcea]

Some rational in bpo-1759169.

[vstinner]

Martin dropped _XOPEN_SOURCE in issue bpo-1759169 (commit 7c947768b435).

--

FYI I changed configure(.in) to get _XOPEN_SOURCE to 700 on OpenBSD 5 to get recent C functions like fdopendir():

  # X/Open 7, incorporating POSIX.1-2008
  AC_DEFINE(_XOPEN_SOURCE, 700,
            Define to the level of X/Open that your system supports)

[tiran]

I think the cause of the bug has been addressed because tests on Solaris are passing.

[neologix]

OK, let's close then.
We can still re-open if this pops up again.