Expose RTLD_* constants in the posix module

[vstinner]

BPO	13226
Nosy	@loewis, @vstinner, @jwilk
Files	posix_rtld.patch posix_rtld-2.patch

^{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 2011-10-25.11:34:21.298>
created_at = <Date 2011-10-19.22:05:43.706>
labels = ['library']
title = 'Expose RTLD_* constants in the posix module'
updated_at = <Date 2013-06-21.15:00:42.103>
user = 'https://github.com/vstinner'

bugs.python.org fields:

activity = <Date 2013-06-21.15:00:42.103>
actor = 'python-dev'
assignee = 'none'
closed = True
closed_date = <Date 2011-10-25.11:34:21.298>
closer = 'vstinner'
components = ['Library (Lib)']
creation = <Date 2011-10-19.22:05:43.706>
creator = 'vstinner'
dependencies = []
files = ['23472', '23483']
hgrepos = []
issue_num = 13226
keywords = ['patch']
message_count = 9.0
messages = ['145975', '146046', '146067', '146074', '146359', '146671', '146688', '146851', '191589']
nosy_count = 6.0
nosy_names = ['loewis', 'vstinner', 'jwilk', 'Arfrever', 'neologix', 'python-dev']
pr_nums = []
priority = 'normal'
resolution = 'fixed'
stage = None
status = 'closed'
superseder = None
type = None
url = 'https://bugs.python.org/issue13226'
versions = ['Python 3.3']

[vstinner]

We have a sys.setdlopenflags() function, but required constants are not available on all platforms. The DLFCN is only available on Linux and sunos5 (is plat-sunos5 available for all Solaris and OpenIndiana versions?), but not on OpenBSD, FreBSD, Mac OS X, ... whereas these platforms have the sys.setdlopenflags() function.

My patch contains 7 constants:

• RTLD_LAZY
• RTLD_NOW
• RTLD_GLOBAL
• RTLD_LOCAL
• RTLD_NODELETE
• RTLD_NOLOAD
• RTLD_DEEPBIND (glibc >= 2.3)

The ctypes has two RTDL constants: RTLD_LOCAL and RTLD_GLOBAL. The 2 constants are always available, even if the platform doesn't support them! Extract of _ctypes.c:
----------------------------------------

/* If RTLD_LOCAL is not defined (Windows!), set it to zero. */
#ifndef RTLD_LOCAL
#define RTLD_LOCAL 0
#endif

/* If RTLD_GLOBAL is not defined (cygwin), set it to the same value as
   RTLD_LOCAL.
*/
#ifndef RTLD_GLOBAL
#define RTLD_GLOBAL RTLD_LOCAL
#endif

---

Lib/plat-sunos5/DLFCN.py contains 25 constants, only 6 are available in my patch. I don't think that we should expose all constants.

Using Google Codesearch, I only found one user of RTLD constants (of the DLFCN module). It's PyKDE4 who calls:

   sys.setdlopenflags(DLFCN.RTLD_NOW|DLFCN.RTLD_GLOBAL)

I guess that the 7 constants should be enough for everyone :-) We may add more later on demand. You can add your own constant to your program if you really need a special option on a specific platform.

[vstinner]

Updated patch: remove "either" in the documentation. Thanks neologix par the review.

[neologix]

Note that I'm really +10 on this issue: such constants belong to individual modules rather than to the unmanageable Lib/plat-XXX/.

[loewis]

The patch looks fine to me. However, I don't think it meets Charles-François' requirement of moving the constants into an individual module. Rather than living in the unmanageable plat-XXX, they now live in the unmanageable posixmodule.c...

[python-dev]

New changeset c75427c0da06 by Victor Stinner in branch 'default':
Issue bpo-13226: Add RTLD_xxx constants to the os module. These constants can by
http://hg.python.org/cpython/rev/c75427c0da06

[Arfrever]

Python/sysmodule.c still contains references to DLFCN module.

[python-dev]

New changeset 05e2bdc00c0c by Victor Stinner in branch 'default':
Issue bpo-13226: Update sys.setdlopenflags() docstring
http://hg.python.org/cpython/rev/05e2bdc00c0c

[vstinner]

sys.getdlopenflags() doc and docstring still contain references to ctypes and DLFCN module.

[python-dev]

New changeset 1da78c7d382b by Andrew Kuchling in branch 'default':
bpo-13226: update references from ctypes/DLFCN modules to os module
http://hg.python.org/cpython/rev/1da78c7d382b