please add posix.getgrouplist()

[ronaldoussoren]

BPO	9344
Nosy	@ronaldoussoren, @abalkin, @pitrou, @giampaolo, @bitdancer
Files	9344.patch: patch to implement getgrouplist for py3k against r87178 9344_v2.patch: Updated 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 2011-06-10.05:59:50.270>
created_at = <Date 2010-07-23.13:10:56.630>
labels = ['extension-modules', 'easy', 'type-feature']
title = 'please add posix.getgrouplist()'
updated_at = <Date 2011-06-16.22:59:08.871>
user = 'https://github.com/ronaldoussoren'

bugs.python.org fields:

activity = <Date 2011-06-16.22:59:08.871>
actor = 'r.david.murray'
assignee = 'rosslagerwall'
closed = True
closed_date = <Date 2011-06-10.05:59:50.270>
closer = 'rosslagerwall'
components = ['Extension Modules']
creation = <Date 2010-07-23.13:10:56.630>
creator = 'ronaldoussoren'
dependencies = []
files = ['20024', '20253']
hgrepos = []
issue_num = 9344
keywords = ['patch', 'easy']
message_count = 16.0
messages = ['111309', '118791', '119062', '119065', '123834', '125293', '125304', '130927', '132021', '132022', '138028', '138049', '138051', '138103', '138105', '138476']
nosy_count = 8.0
nosy_names = ['ronaldoussoren', 'belopolsky', 'pitrou', 'giampaolo.rodola', 'r.david.murray', 'nvetoshkin', 'rosslagerwall', 'python-dev']
pr_nums = []
priority = 'low'
resolution = 'fixed'
stage = 'resolved'
status = 'closed'
superseder = None
type = 'enhancement'
url = 'https://bugs.python.org/issue9344'
versions = ['Python 3.3']

[ronaldoussoren]

A number of unix systems expose a getgroupslist function to fetch the groups that a user is a member of. It would be nice if that function were exposed to python.

See bpo-7900 for more information on why that would be useful.

[nvetoshkin]

Did a bit of digging and found that getgrouplist signature differs on (at least) Linux and Mac OS:

• http://www.kernel.org/doc/man-pages/online/pages/man3/getgrouplist.3.html
  -http://developer.apple.com/library/mac/#documentation/Darwin/Reference/ManPages/man3/getgrouplist.3.html

[abalkin]

I don't see how this difference is relevant for exposing the functionality in python:

Linux:

int getgrouplist(const char *user, gid_t group,
                        gid_t *groups, int *ngroups);

MacOS:

int
     getgrouplist(const char *name, int basegid, int *groups, int *ngroups);

The only difference is that Linux uses gid_t and MacOS uses int. The requested posix.getgrouplist() will take a python string and a python integer and return a list of integers.

[nvetoshkin]

@alexander, it was just a note, that implementation in posixmodule.c won't be the same across all flavours of Unix :)

[rosslagerwall]

Attached is a patch (against the latest revision, 87178) which adds the functionality to the posix module as well as adds a testcase for it.

I haven't added it to the os module, I'm not sure if that should be done.

I tested it on Linux & FreeBSD and it works as expected. Since I don't have an OS X system, I could not test it on there.

[rosslagerwall]

A slightly updated patch. Targeting for 3.3.

[pitrou]

I can't say anything about the functionality, but the patch looks good to me (works under Linux and Solaris - the latter missing getgrouplist()).

[ronaldoussoren]

Patch looks good, but this likely runs into the same problem as bpo-7900: the user can be a member of more than NGROUPS_MAX on OSX.

I'll test this tomorrow (by creating a temporary user that is a member of more than 16 groups).

[abalkin]

Looks good to me as well. Just a nit-pick: in python code base "sizeof" is not separated from the opening parenthesis. I understand the desire to distinguish "sizeof" from a function, but it is probably better to be consistent.

[rosslagerwall]

Ronald, does it have the same problem as bpo-7900 on OS X or can I commit?

[ronaldoussoren]

I haven't tested yet, but feel free to commit and I'll fix any OSX issues later.

[python-dev]

New changeset 9ebee3211be9 by Ross Lagerwall in branch 'default':
Issue bpo-9344: Add os.getgrouplist().
http://hg.python.org/cpython/rev/9ebee3211be9

[rosslagerwall]

Thanks!

[pitrou]

Nit: when a patch gets committed and the issue closed, the preferred resolution is "fixed" ;)
(see http://docs.python.org/devguide/triaging.html#resolution)

[rosslagerwall]

Nit: when a patch gets committed and the issue closed, the preferred
resolution is "fixed" ;)
(see http://docs.python.org/devguide/triaging.html#resolution)

Sure, I will try remember that.

[bitdancer]

Actually, when it is a feature request rather than a bug fix we usually use 'accepted'. It doesn't matter a whole lot, though.