Co-authored-by: Konge <zkonge@outlook.com>

PyConfig_InitPythonConfig() and PyConfig_InitIsolatedConfig() no
longer return PyStatus: they cannot fail anymore.
(cherry picked from commit 8462a4936b3a551dc546a6adea04a70b0a07ca67)

Co-authored-by: Victor Stinner <vstinner@redhat.com>

For now, we'll rely on the fact that the config structures aren't covered by the stable ABI.

We may revisit this in the future if we further explore the idea of offering a stable embedding API.

Fix warnings options priority: PyConfig.warnoptions has the highest
priority, as stated in the PEP 587.

* Document options order in PyConfig.warnoptions documentation.
* Make PyWideStringList_INIT macro private: replace "Py" prefix
  with "_Py".
* test_embed: add test_init_warnoptions().
(cherry picked from commit fb4ae152a9930f0e00cae8b2807f534058cf341a)

Co-authored-by: Victor Stinner <vstinner@redhat.com>

Add a new struct_size field to PyPreConfig and PyConfig structures to
allow to modify these structures in the future without breaking the
backward compatibility.

* Replace private _config_version field with public struct_size field
  in PyPreConfig and PyConfig.
* Public PyPreConfig_InitIsolatedConfig() and
  PyPreConfig_InitPythonConfig()
  return type becomes PyStatus, instead of void.
* Internal _PyConfig_InitCompatConfig(),
  _PyPreConfig_InitCompatConfig(), _PyPreConfig_InitFromConfig(),
  _PyPreConfig_InitFromPreConfig() return type becomes PyStatus,
  instead of void.
* Remove _Py_CONFIG_VERSION
* Update the Initialization Configuration documentation.

(cherry picked from commit 441b10cf2855955c86565f8d59e72c2efc0f0a57)

* bpo-38234: Py_SetPath() uses the program full path (GH-16357)

Py_SetPath() now sets sys.executable to the program full path
(Py_GetProgramFullPath()), rather than to the program name
(Py_GetProgramName()).

Fix also memory leaks in pathconfig_set_from_config().

(cherry picked from commit 1ce152a42eaa917d7763bce93f1e1ca72530d7ca)

* bpo-38234: Add tests for Python init path config (GH-16358)


(cherry picked from commit bb6bf7d342b4503a6227fd209fac934905b6a1aa)

* bpo-38234: test_embed: test pyvenv.cfg and pybuilddir.txt (GH-16366)

Add test_init_pybuilddir() and test_init_pyvenv_cfg() to test_embed
to test pyvenv.cfg and pybuilddir.txt configuration files.

Fix sysconfig._generate_posix_vars(): pybuilddir.txt uses UTF-8
encoding, not ASCII.

(cherry picked from commit 52ad33abbfb6637d74932617c7013bae0ccf6e32)

* bpo-38234: Cleanup getpath.c (GH-16367)

* search_for_prefix() directly calls reduce() if found is greater
  than 0.
* Add calculate_pybuilddir() subfunction.
* search_for_prefix(): add path string buffer for readability.
* Fix some error handling code paths: release resources on error.
* calculate_read_pyenv(): rename tmpbuffer to filename.
* test.pythoninfo now also logs windows.dll_path

(cherry picked from commit 221fd84703c545408bbb4a6e0b58459651331f5c)

* bpo-38234: Fix test_embed pathconfig tests (GH-16390)

bpo-38234: On macOS and FreeBSD, the temporary directory can be
symbolic link. For example, /tmp can be a symbolic link to /var/tmp.
Call realpath() to resolve all symbolic links.

(cherry picked from commit 00508a7407d7d300b487532e2271534b20e378a7)

* bpo-38234: Add test_init_setpath_config() to test_embed (GH-16402)

* Add test_embed.test_init_setpath_config(): test Py_SetPath()
  with PyConfig.
* test_init_setpath() and test_init_setpythonhome() no longer call
  Py_SetProgramName(), but use the default program name.
* _PyPathConfig: isolated, site_import  and base_executable
  fields are now only available on Windows.
* If executable is set explicitly in the configuration, ignore
  calculated base_executable: _PyConfig_InitPathConfig() copies
  executable to base_executable.
* Complete path config documentation.

(cherry picked from commit 8bf39b606ef7b02c0279a80789f3c4824b0da5e9)

* bpo-38234: Complete init config documentation (GH-16404)


(cherry picked from commit 88feaecd46a8f427e30ef7ad8cfcddfe392a2402)

* bpo-38234: Fix test_embed.test_init_setpath_config() on FreeBSD (GH-16406)

Explicitly preinitializes with a Python preconfiguration to avoid
Py_SetPath() implicit preinitialization with a compat
preconfiguration.

Fix also test_init_setpath() and test_init_setpythonhome() on macOS:
use self.test_exe as the executable (and base_executable), rather
than shutil.which('python3').

(cherry picked from commit 49d99f01e6e51acec5ca57a02e857f0796bc418b)

* bpo-38234: Py_Initialize() sets global path configuration (GH-16421)

* Py_InitializeFromConfig() now writes PyConfig path configuration to
  the global path configuration (_Py_path_config).
* Add test_embed.test_get_pathconfig().
* Fix typo in _PyWideStringList_Join().

(cherry picked from commit 12f2f177fc483723406d7917194e7f655a20631b)

PyConfig_Read() is now responsible to handle early calls to
PySys_AddXOption() and PySys_AddWarnOption().

Options added by PySys_AddXOption() are now handled the same way than
PyConfig.xoptions and command line -X options.

For example, PySys_AddXOption(L"faulthandler") enables faulthandler
as expected.

(cherry picked from commit 120b707a6d43452e067daa55a8fdca69f9424abc)

(cherry picked from commit 3842f2997fbd4dc840986aad2bb94656815e243b)

Co-authored-by: Victor Stinner <vstinner@redhat.com>

(cherry picked from commit e226e83d36dfc7220d836fb7a249ce18e70cb4a6)

Co-authored-by: Steve Dower <steve.dower@python.org>

Stop using "static PyConfig", PyConfig must now always use
dynamically allocated strings: use PyConfig_SetString(),
PyConfig_SetArgv() and PyConfig_Clear().
(cherry picked from commit 67310023f299b5a2fad71fca449b46d280036690)

Co-authored-by: Victor Stinner <vstinner@redhat.com>