Python get "user cache directory" on any OS

_cachedir.py

# Usage:
#     import _cachedir
#     CACHEDIR = _cachedir.cachedir('my_application@company.com')
#     CACHEDIR = _cachedir.cachedir('my_packagename@pypi.org')

# NOTE:
# This does not create a secure enclave of any kind.
# Obviously, malicious applications running on the same
# user account could read or modify the cache directory.

import os
from pathlib import Path
import platform
import re
import sys
import uuid

# https://hg.mozilla.org/releases/mozilla-release/file/652f653a58f0acdc1413e45ab35eae68a95cd1af/toolkit/mozapps/extensions/internal/XPIInstall.jsm#l178
UNIQUE_REGEX = re.compile(r'^(\{[0-9a-f]{8}-[0-9a-f]{4}-[0-9a-f]{4}-[0-9a-f]{4}-[0-9a-f]{12}\}|[a-z0-9-\._]*\@[a-z0-9-\._]+)$')

UMASK_PRIVDIR = 0o0700

__all__ = ['cachedir']


def cachedir(name):
	if not UNIQUE_REGEX.match(name):
		if '@' not in name and len(name) < 30:
			raise ValueError(f'bad application ID. Did you mean {f"{name}@pypi.org"!r}?')
		raise ValueError('bad application ID.')

	app_dir = _base_usercachedir() / name
	os.makedirs(app_dir, UMASK_PRIVDIR, exist_ok=True)
	return app_dir


def _base_usercachedir():
	system = platform.system()
	if system == 'Windows':
		# https://learn.microsoft.com/en-us/windows/win32/shell/knownfolderid#FOLDERID_LOCALAPPDATA
		return Path(_shell32_known_folder('F1B32785-6FBA-4FCF-9D55-7B8E7F157091'))

	elif system == 'Darwin':
		# FIXME https://developer.apple.com/documentation/foundation/filemanager/searchpathdirectory/cachesdirectory
		return Path('~/Library/Caches').expanduser()

	else:
		# https://specifications.freedesktop.org/basedir-spec/latest/ar01s03.html
		if not (system == 'Linux' or system.endswith('BSD') or system == 'AIX'):
			warnings.warn(f'Unrecognized operating system, {system!r}')

		if ['XDG_CACHE_HOME'] in os.environ:
			return Path(os.environ['XDG_CACHE_HOME'])
		else:
			return Path('~/.cache').expanduser()


if platform.system() == 'Windows':
	from contextlib import contextmanager
	import ctypes
	from ctypes import oledll
	from ctypes import windll
	import ctypes.wintypes
	try:
		wintypes_GUID = ctypes.wintypes.GUID
	except AttributeError:
		class wintypes_GUID(ctypes.Structure):
			# https://learn.microsoft.com/en-us/windows/win32/api/guiddef/ns-guiddef-guid
			_fields_ = [
				('Data1', ctypes.c_ulong),
				('Data2', ctypes.c_ushort),
				('Data3', ctypes.c_ushort),
				('Data4', ctypes.c_ubyte * 8)
			]
			def __init__(self, guid=None):
				super().__init__()  # NOTE is this needed??
				if guid is not None:
				# https://learn.microsoft.com/en-us/windows/win32/api/combaseapi/nf-combaseapi-clsidfromstring
					if not isinstance(guid, uuid.UUID):
						guid = uuid.UUID(guid)
					clsid = f'{{{guid!s}}}'
					errno = oledll.ole32.CLSIDFromString(clsid, ctypes.byref(self))
					if errno != 0:
						raise RuntimeError(f'CLSIDFromString returned error code {errno}')

	def _shell32_known_folder(guid, /, *, _flags=0, _handle=None):
		folder_id = wintypes_GUID(guid)
		result_ptr = ctypes.c_wchar_p()
		with _freeing(oledll.ole32.CoTaskMemFree, result_ptr):
			errno = windll.shell32.SHGetKnownFolderPath(
				ctypes.byref(folder_id),
				_flags,
				_handle,
				ctypes.byref(result_ptr)
			)
			if errno == 0:
				return result_ptr.value
			else:
				raise RuntimeError(f'SHGetKnownFolderPath returned error code {errno}')

	@contextmanager
	def _freeing(freefunc, obj):
		try:
			yield obj
		finally:
			freefunc(obj)