python: add qemu package installer

Add setup.cfg and setup.py, necessary for installing a package via
pip. Add a ReST document (PACKAGE.rst) explaining the basics of what
this package is for and who to contact for more information. This
document will be used as the landing page for the package on PyPI.

List the subpackages we intend to package by name instead of using
find_namespace because find_namespace will naively also packages tests,
things it finds in the dist/ folder, etc. I could not figure out how to
modify this behavior; adding allow/deny lists to setuptools kept
changing the packaged hierarchy. This works, roll with it.

I am not yet using a pyproject.toml style package manifest, because
"editable" installs are not defined (yet?) by PEP-517/518.

I consider editable installs crucial for development, though they have
(apparently) always been somewhat poorly defined.

Pip now (19.2 and later) now supports editable installs for projects
using pyproject.toml manifests, but might require the use of the
--no-use-pep517 flag, which somewhat defeats the point. Full support for
setup.py-less editable installs was not introduced until pip 21.1.1:
pypa/pip@7a95720

For now, while the dust settles, stick with the de-facto
setup.py/setup.cfg combination supported by setuptools. It will be worth
re-evaluating this point again in the future when our supported build
platforms all ship a fairly modern pip.

Additional reading on this matter:

pypa/packaging-problems#256
pypa/pip#6334
pypa/pip#6375
pypa/pip#6434
pypa/pip#6438

Signed-off-by: John Snow <jsnow@redhat.com>
Reviewed-by: Vladimir Sementsov-Ogievskiy <vsementsov@virtuozzo.com>
Reviewed-by: Cleber Rosa <crosa@redhat.com>
Message-id: 20210527211715.394144-11-jsnow@redhat.com
Signed-off-by: John Snow <jsnow@redhat.com>

python/PACKAGE.rst

@@ -0,0 +1,33 @@
+QEMU Python Tooling
+===================
+
+This package provides QEMU tooling used by the QEMU project to build,
+configure, and test QEMU. It is not a fully-fledged SDK and it is subject
+to change at any time.
+
+Usage
+-----
+
+The ``qemu.qmp`` subpackage provides a library for communicating with
+QMP servers. The ``qemu.machine`` subpackage offers rudimentary
+facilities for launching and managing QEMU processes. Refer to each
+package's documentation
+(``>>> help(qemu.qmp)``, ``>>> help(qemu.machine)``)
+for more information.
+
+Contributing
+------------
+
+This package is maintained by John Snow <jsnow@redhat.com> as part of
+the QEMU source tree. Contributions are welcome and follow the `QEMU
+patch submission process
+<https://wiki.qemu.org/Contribute/SubmitAPatch>`_, which involves
+sending patches to the QEMU development mailing list.
+
+John maintains a `GitLab staging branch
+<https://gitlab.com/jsnow/qemu/-/tree/python>`_, and there is an
+official `GitLab mirror <https://gitlab.com/qemu-project/qemu>`_.
+
+Please report bugs on the `QEMU issue tracker
+<https://gitlab.com/qemu-project/qemu/-/issues>`_ and tag ``@jsnow`` in
+the report.

python/setup.cfg

@@ -0,0 +1,22 @@
+[metadata]
+name = qemu
+maintainer = QEMU Developer Team
+maintainer_email = qemu-devel@nongnu.org
+url = https://www.qemu.org/
+download_url = https://www.qemu.org/download/
+description = QEMU Python Build, Debug and SDK tooling.
+long_description = file:PACKAGE.rst
+long_description_content_type = text/x-rst
+classifiers =
+    Development Status :: 3 - Alpha
+    License :: OSI Approved :: GNU General Public License v2 (GPLv2)
+    Natural Language :: English
+    Operating System :: OS Independent
+    Programming Language :: Python :: 3 :: Only
+
+[options]
+python_requires = >= 3.6
+packages =
+    qemu.qmp
+    qemu.machine
+    qemu.utils

python/setup.py

@@ -0,0 +1,23 @@
+#!/usr/bin/env python3
+"""
+QEMU tooling installer script
+Copyright (c) 2020-2021 John Snow for Red Hat, Inc.
+"""
+
+import setuptools
+import pkg_resources
+
+
+def main():
+    """
+    QEMU tooling installer
+    """
+
+    # https://medium.com/@daveshawley/safely-using-setup-cfg-for-metadata-1babbe54c108
+    pkg_resources.require('setuptools>=39.2')
+
+    setuptools.setup()
+
+
+if __name__ == '__main__':
+    main()