Edit: pep514.py
"""Implement https://www.python.org/dev/peps/pep-0514/ to discover interpreters - Windows only.""" from __future__ import annotations import os import re import winreg from logging import basicConfig, getLogger LOGGER = getLogger(__name__) def enum_keys(key): at = 0 while True: try: yield winreg.EnumKey(key, at) except OSError: break at += 1 def get_value(key, value_name): try: return winreg.QueryValueEx(key, value_name)[0] except OSError: return None def discover_pythons(): for hive, hive_name, key, flags, default_arch in [ (winreg.HKEY_CURRENT_USER, "HKEY_CURRENT_USER", r"Software\Python", 0, 64), (winreg.HKEY_LOCAL_MACHINE, "HKEY_LOCAL_MACHINE", r"Software\Python", winreg.KEY_WOW64_64KEY, 64), (winreg.HKEY_LOCAL_MACHINE, "HKEY_LOCAL_MACHINE", r"Software\Python", winreg.KEY_WOW64_32KEY, 32), ]: yield from process_set(hive, hive_name, key, flags, default_arch) def process_set(hive, hive_name, key, flags, default_arch): try: with winreg.OpenKeyEx(hive, key, 0, winreg.KEY_READ | flags) as root_key: for company in enum_keys(root_key): if company == "PyLauncher": # reserved continue yield from process_company(hive_name, company, root_key, default_arch) except OSError: pass def process_company(hive_name, company, root_key, default_arch): with winreg.OpenKeyEx(root_key, company) as company_key: for tag in enum_keys(company_key): spec = process_tag(hive_name, company, company_key, tag, default_arch) if spec is not None: yield spec def process_tag(hive_name, company, company_key, tag, default_arch): with winreg.OpenKeyEx(company_key, tag) as tag_key: version = load_version_data(hive_name, company, tag, tag_key) if version is not None: # if failed to get version bail major, minor, _ = version arch = load_arch_data(hive_name, company, tag, tag_key, default_arch) if arch is not None: exe_data = load_exe(hive_name, company, company_key, tag) if exe_data is not None: exe, args = exe_data threaded = load_threaded(hive_name, company, tag, tag_key) return company, major, minor, arch, threaded, exe, args return None return None return None def load_exe(hive_name, company, company_key, tag): key_path = f"{hive_name}/{company}/{tag}" try: with winreg.OpenKeyEx(company_key, rf"{tag}\InstallPath") as ip_key, ip_key: exe = get_value(ip_key, "ExecutablePath") if exe is None: ip = get_value(ip_key, None) if ip is None: msg(key_path, "no ExecutablePath or default for it") else: exe = os.path.join(ip, "python.exe") if exe is not None and os.path.exists(exe): args = get_value(ip_key, "ExecutableArguments") return exe, args msg(key_path, f"could not load exe with value {exe}") except OSError: msg(f"{key_path}/InstallPath", "missing") return None def load_arch_data(hive_name, company, tag, tag_key, default_arch): arch_str = get_value(tag_key, "SysArchitecture") if arch_str is not None: key_path = f"{hive_name}/{company}/{tag}/SysArchitecture" try: return parse_arch(arch_str) except ValueError as sys_arch: msg(key_path, sys_arch) return default_arch def parse_arch(arch_str): if isinstance(arch_str, str): match = re.match(r"^(\d+)bit$", arch_str) if match: return int(next(iter(match.groups()))) error = f"invalid format {arch_str}" else: error = f"arch is not string: {arch_str!r}" raise ValueError(error) def load_version_data(hive_name, company, tag, tag_key): for candidate, key_path in [ (get_value(tag_key, "SysVersion"), f"{hive_name}/{company}/{tag}/SysVersion"), (tag, f"{hive_name}/{company}/{tag}"), ]: if candidate is not None: try: return parse_version(candidate) except ValueError as sys_version: msg(key_path, sys_version) return None def parse_version(version_str): if isinstance(version_str, str): match = re.match(r"^(\d+)(?:\.(\d+))?(?:\.(\d+))?$", version_str) if match: return tuple(int(i) if i is not None else None for i in match.groups()) error = f"invalid format {version_str}" else: error = f"version is not string: {version_str!r}" raise ValueError(error) def load_threaded(hive_name, company, tag, tag_key): display_name = get_value(tag_key, "DisplayName") if display_name is not None: if isinstance(display_name, str): if "freethreaded" in display_name.lower(): return True else: key_path = f"{hive_name}/{company}/{tag}/DisplayName" msg(key_path, f"display name is not string: {display_name!r}") return bool(re.match(r"^\d+(\.\d+){0,2}t$", tag, flags=re.IGNORECASE)) def msg(path, what): LOGGER.warning("PEP-514 violation in Windows Registry at %s error: %s", path, what) def _run(): basicConfig() interpreters = [repr(spec) for spec in discover_pythons()] print("\n".join(sorted(interpreters))) # noqa: T201 if __name__ == "__main__": _run()
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