Building Python on Linux/Unix
=============================

On these OS'es, we build Python from its sources ourselves. As Python 2.7 is
no longer maintained upstream, security patches are lifted from
ActiveState's fork: https://github.com/ActiveState/cpython/commits/2.7 and
https://git.centos.org/rpms/python/blob/c7/f/SOURCES. Another relevant source:
https://packages.debian.org/bullseye/python2.7-minimal.

E.g. to fix CVE-2020-10735 from ActiveState/cpython#18,
use https://github.com/ActiveState/cpython/pull/18.diff to save the patch
to apply to our Python sources tree, then issue something like:

    cd Python-2.7.18
    patch -p1 < ~/Downloads/CVE-2020-10735.diff

Python sources are currently patched from upstream Active State branch up to and
including fixes from Aug 22, 2024 for ActiveState Python version 2.7.18.10.

Patches that can be applied on Windows as hot fixes (see below for more details)
are saved as diff files in the current directory. They are also applied on
non-Windows platforms before building Python.


Building Python on Windows
==========================

Building Python on Windows is something of a black art. So we don't build
Python from source on this OS, we use the already-compiled upstream Python
package instead. Therefore, only patches to Python code can be applied.
Patches to C code cannot be applied on Windows through our build system.


Patching Python code
--------------------

To have a Python-only patch automatically applied on Windows, save it as
a ".diff" file in this sub-dir, e.g. "CVE-2015-20107.diff". If it doesn't apply
cleanly, try adapting it to our sources. This patch in particular (actually
written in 2023) was edited to remove patching for tests that are only present
in ActiveState's fork.

These ".diff" patches (called hot fixes in our scripts) are copied over
automatically before "building" Python on Windows, alongside the original
"*.patch" fixes. The `chevahbs` script in this sub-dir is going to patch
the ".diff" patches on Windows, ordered by filename.


Building Python modules
-----------------------

Even though we don't build Python on Windows, we do compile some Python modules.

Systems on which this Python distribution is built need to have at least:

* Microsoft Visual C++ Redistributable for Visual Studio 2008 (VC+ 9.0) from
  https://support.microsoft.com/en-us/kb/2977003
* Microsoft Visual C++ Compiler for Python 2.7 from
  https://www.microsoft.com/en-us/download/details.aspx?id=44266

Alternatively, install the `vcredist2008` and `vcpython2` Chocolatey packages.

To not require the Visual Studio 2008 (VC++ 9.0) redistributable on the systems
running this Python package, the needed DLLs and their manifests are copied
over from the `win-tools/redistributables` sub-directory of this repository
at build time. To update them, follow the instructions in `win-tools/README`.

MSI installers for both x86 and amd64, downloaded from the official Python
website, should be present in the `src/python/Python-$VERSION-windows/`
sub-directory (where $VERSION is the latest Python 2.7 version.)

For pip, copy latest `get-pip.py` to `python-modules/get-pip.py`.

All needed sources and wheels should be present on the custom PyPI server at
https://bin.chevah.com:20443/pypi.

Please note that VC compiler is used by default by pip. To manually enable
it, make sure you have latest setuptools:

1. Enter MSVC for Python command prompt
2. SET DISTUTILS_USE_SDK=1
3. SET MSSdk=1
4. python.exe setup.py build