Fixed issues with encodings and wine / proton compatibilities.

ptlinux/settings.py

@@ -2,14 +2,21 @@
 
 from __future__ import annotations
 
-from dataclasses import asdict, dataclass
+from dataclasses import asdict, dataclass, fields, replace
 import json
 import os
 from pathlib import Path
+import secrets
+import threading
+from typing import Any
 
+from .locking import launcher_operation_lock
 from .paths import AppPaths
 
 
+SETTINGS_SCHEMA = 1
+
+
 @dataclass(frozen=True)
 class Settings:
 	width: int = 1600
@@ -33,14 +40,98 @@ class Settings:
 
 
 def load_settings(paths: AppPaths) -> Settings:
-	try:
-		value = json.loads(paths.settings_file.read_text(encoding="utf-8"))
-	except FileNotFoundError:
+	value = _read_settings_object(paths.settings_file)
+	if value is None:
 		return Settings()
-	except (OSError, json.JSONDecodeError) as exc:
-		raise ValueError(f"invalid settings file {paths.settings_file}: {exc}") from exc
+	return _settings_from_object(value)
+
+
+def save_settings(paths: AppPaths, settings: Settings) -> Settings:
+	"""Atomically save a complete settings snapshot.
+
+	Unknown fields from a newer launcher are retained when the existing file is
+	valid. Callers editing only part of the configuration should use
+	``update_settings`` so an old in-memory snapshot cannot undo another save.
+	"""
+
+	_validate(settings)
+	paths.config.mkdir(parents=True, exist_ok=True)
+	with launcher_operation_lock(paths.settings_lock, "settings-save"):
+		existing = _read_settings_object(paths.settings_file)
+		_write_settings(paths, settings, existing)
+	return settings
+
+
+def update_settings(paths: AppPaths, **changes: Any) -> Settings:
+	"""Merge selected settings into the newest on-disk configuration."""
+
+	unknown = set(changes).difference(_SETTINGS_FIELD_NAMES)
+	if unknown:
+		names = ", ".join(sorted(unknown))
+		raise ValueError(f"unsupported launcher setting: {names}")
+	paths.config.mkdir(parents=True, exist_ok=True)
+	with launcher_operation_lock(paths.settings_lock, "settings-update"):
+		existing = _read_settings_object(paths.settings_file)
+		current = (
+			_settings_from_object(existing)
+			if existing is not None
+			else Settings()
+		)
+		updated = replace(current, **changes)
+		_validate(updated)
+		_write_settings(paths, updated, existing)
+	return updated
+
+
+def ensure_settings(paths: AppPaths) -> Settings:
+	"""Create settings once and materialize defaults added by newer releases."""
+
+	paths.config.mkdir(parents=True, exist_ok=True)
+	with launcher_operation_lock(paths.settings_lock, "settings-migrate"):
+		existing = _read_settings_object(paths.settings_file)
+		if existing is None:
+			settings = Settings()
+			_write_settings(paths, settings, None)
+			return settings
+		settings = _settings_from_object(existing)
+		if _settings_need_migration(existing):
+			_write_settings(paths, settings, existing)
+		return settings
+
+
+def reset_settings(paths: AppPaths) -> Settings:
+	"""Replace all launcher settings with the documented defaults."""
+
+	settings = Settings()
+	paths.config.mkdir(parents=True, exist_ok=True)
+	with launcher_operation_lock(paths.settings_lock, "settings-reset"):
+		_write_settings(paths, settings, None)
+	return settings
+
+
+def _read_settings_object(path: Path) -> dict[str, object] | None:
+	try:
+		content = path.read_bytes()
+	except FileNotFoundError:
+		return None
+	except OSError as exc:
+		raise ValueError(f"invalid settings file {path}: {exc}") from exc
+	try:
+		value = json.loads(_decode_settings(content))
+	except (UnicodeError, json.JSONDecodeError) as exc:
+		raise ValueError(f"invalid settings file {path}: {exc}") from exc
 	if not isinstance(value, dict):
-		raise ValueError(f"settings file must contain an object: {paths.settings_file}")
+		raise ValueError(f"settings file must contain an object: {path}")
+	schema = value.get("schema")
+	if schema is not None:
+		if isinstance(schema, bool) or not isinstance(schema, int):
+			raise ValueError(f"settings schema must be an integer: {path}")
+		if schema != SETTINGS_SCHEMA:
+			raise ValueError(f"unsupported settings schema {schema}: {path}")
+	return value
+
+
+def _settings_from_object(value: dict[str, object]) -> Settings:
 	settings = Settings(
 		width=_integer(value, "width", 1600),
 		height=_integer(value, "height", 900),
@@ -65,25 +156,62 @@ def load_settings(paths: AppPaths) -> Settings:
 	return settings
 
 
-def save_settings(paths: AppPaths, settings: Settings) -> None:
-	_validate(settings)
-	paths.config.mkdir(parents=True, exist_ok=True)
+def _decode_settings(content: bytes) -> str:
+	"""Accept native UTF-8 plus settings saved by common Windows editors."""
+
+	try:
+		return content.decode("utf-8-sig")
+	except UnicodeDecodeError as utf8_error:
+		try:
+			return content.decode("cp1252")
+		except UnicodeDecodeError:
+			raise utf8_error
+
+
+def _settings_need_migration(value: dict[str, object]) -> bool:
+	return (
+		value.get("schema") != SETTINGS_SCHEMA
+		or not _SETTINGS_FIELD_NAMES.issubset(value)
+	)
+
+
+def _write_settings(
+	paths: AppPaths,
+	settings: Settings,
+	existing: dict[str, object] | None,
+) -> None:
+	payload = dict(existing or {})
+	payload.update(asdict(settings))
+	payload["schema"] = SETTINGS_SCHEMA
 	temporary = paths.settings_file.with_name(
-		f".{paths.settings_file.name}.{os.getpid()}.tmp"
+		f".{paths.settings_file.name}.{os.getpid()}.{threading.get_ident()}."
+		f"{secrets.token_hex(8)}.tmp"
 	)
-	temporary.write_text(
-		json.dumps(asdict(settings), indent=2, sort_keys=True) + "\n",
-		encoding="utf-8",
-	)
-	temporary.replace(paths.settings_file)
+	try:
+		with temporary.open("x", encoding="utf-8", newline="\n") as handle:
+			json.dump(payload, handle, indent=2, sort_keys=True)
+			handle.write("\n")
+			handle.flush()
+			os.fsync(handle.fileno())
+		temporary.chmod(0o600)
+		os.replace(temporary, paths.settings_file)
+		_fsync_directory(paths.config)
+	except BaseException:
+		temporary.unlink(missing_ok=True)
+		raise
 
 
-def ensure_settings(paths: AppPaths) -> Settings:
-	if paths.settings_file.exists():
-		return load_settings(paths)
-	settings = Settings()
-	save_settings(paths, settings)
-	return settings
+def _fsync_directory(path: Path) -> None:
+	try:
+		descriptor = os.open(path, os.O_RDONLY | getattr(os, "O_DIRECTORY", 0))
+	except OSError:
+		return
+	try:
+		os.fsync(descriptor)
+	except OSError:
+		pass
+	finally:
+		os.close(descriptor)
 
 
 def _validate(settings: Settings) -> None:
@@ -135,3 +263,6 @@ def _optional_string(value: dict[str, object], key: str) -> str | None:
 	if not isinstance(item, str) or not item:
 		raise ValueError(f"{key} must be null or a non-empty string")
 	return item
+
+
+_SETTINGS_FIELD_NAMES = frozenset(field.name for field in fields(Settings))