Re: [PATCH 1/1] libselinux, libsemanage: Replace PYSITEDIR with PYTHONLIBDIR

From: Petr Lautrbach <plautrba@redhat.com>
To: Nicolas Iooss <nicolas.iooss@m4x.org>
Cc: Stephen Smalley <sds@tycho.nsa.gov>, selinux <selinux@tycho.nsa.gov>
Subject: Re: [PATCH 1/1] libselinux, libsemanage: Replace PYSITEDIR with PYTHONLIBDIR
Date: Fri, 9 Mar 2018 13:25:56 +0100	[thread overview]
Message-ID: <20180309122556.GA3849@workstation> (raw)
In-Reply-To: <CAJfZ7==qgVM0KwHdSJ2z7E4iifTx-CPjT3ikFfX4iorG6vOAXw@mail.gmail.com>

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On Thu, Mar 08, 2018 at 10:19:26PM +0100, Nicolas Iooss wrote:
> On Thu, Mar 8, 2018 at 8:34 PM, Stephen Smalley <sds@tycho.nsa.gov> wrote:
> > On 03/06/2018 04:19 PM, Stephen Smalley wrote:
> >> On 03/05/2018 05:16 PM, Nicolas Iooss wrote:
> >>> libselinux and libsemanage Makefiles invoke site.getsitepackages() in
> >>> order to get the path to the directory /usr/lib/pythonX.Y/site-packages
> >>> that matches the Python interpreter chosen with $(PYTHON). This method
> >>> is incompatible with Python virtual environments, as described in
> >>> https://github.com/pypa/virtualenv/issues/355#issuecomment-10250452 .
> >>> This issue has been opened for more than 5 years.
> >>>
> >>> On the contrary python/semanage/ and python/sepolgen/ Makefiles use
> >>> distutils.sysconfig.get_python_lib() in order to get the site-packages
> >>> path into a variable named PYTHONLIBDIR. This way of computing
> >>> PYTHONLIBDIR is compatible with virtual environments and gives the same
> >>> result as PYSITEDIR.
> >>>
> >>> As PYTHONLIBDIR works in more cases than PYSITEDIR, make libselinux and
> >>> libsemanage Makefiles use it.
> >>
> >> On Fedora x86_64, this changes the install location from /usr/lib64 to /usr/lib.
> >
> > That said I agree we ought to be consistent, and it does seem that we are not currently.
> > I'm just not sure what the best fix is in this case and the impact on distro packagers.
> 
> Good point. I have read
> https://marc.info/?l=selinux&m=151670320132614&w=2 too quickly (and
> missed "given that there's only pure python modules"). This message
> suggests that doing using get_python_lib(plat_specific=1) would keep
> /usr/lib64 on Fedora (unfortunately I only have access to Debian,
> Ubuntu and Arch Linux systems right now so I am not able to test).

On Fedora Rawhide:

>>> get_python_lib()
'/usr/lib/python3.6/site-packages'
>>> get_python_lib(plat_specific=1)
'/usr/lib64/python3.6/site-packages'
>>> get_python_lib(prefix='/usr/local')
'/usr/local/lib/python3.6/site-packages'
>>> get_python_lib(prefix='/usr/local', plat_specific=1)
'/usr/local/lib64/python3.6/site-packages'

> And
> to be consistent, I suggest naming the variable differently from
> PYTHONLIBDIR. For example:
> 
> PYTHONPLATLIBDIR ?= $(shell $(PYTHON) -c "from distutils.sysconfig
> import *; print(get_python_lib(plat_specific=1, prefix='$(PREFIX)'))")
> 
> ... or PYPLATLIBDIR if PYTHONPLATLIBDIR is too long. Or we also can
> keep the name PYSITEDIR while changing its definition, in order to
> minimize the impact. What would be acceptable?
>

Given that libselinux and libsemanage provides only extension SWIG generated
modules I'd just set plat_specific=1 and use PYTHONLIBDIR in this case.

> Cheers,
> Nicolas
> 

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