Init

ptdiag/registry.py

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+"""Read-only Wine registry snapshots for reversible desktop configuration."""
+
+from __future__ import annotations
+
+import ast
+from dataclasses import asdict, dataclass
+from pathlib import Path
+import re
+
+from .filesystem import sha256_file
+
+
+_VALUE_RE = re.compile(r'^(?P<name>"(?:\\.|[^"\\])*")=(?P<value>.*)$')
+_SECTION_RE = re.compile(r"^\[(?P<name>.*)\](?:\s+[0-9]+)?$")
+
+
+@dataclass(frozen=True)
+class RegistryValue:
+	exists: bool
+	value: str | None
+
+	def to_dict(self) -> dict[str, str | bool | None]:
+		return asdict(self)
+
+
+@dataclass(frozen=True)
+class DesktopRegistrySnapshot:
+	user_reg: Path
+	sha256: str
+	desktop_name: str
+	selected_desktop: RegistryValue
+	desktop_size: RegistryValue
+
+	def to_dict(self) -> dict[str, object]:
+		return {
+			"user_reg": str(self.user_reg),
+			"sha256": self.sha256,
+			"desktop_name": self.desktop_name,
+			"selected_desktop": self.selected_desktop.to_dict(),
+			"desktop_size": self.desktop_size.to_dict(),
+		}
+
+
+def snapshot_desktop_registry(prefix: Path, desktop_name: str) -> DesktopRegistrySnapshot:
+	user_reg = prefix / "user.reg"
+	sections = read_registry_string_values(user_reg)
+	selected = sections.get(r"Software\Wine\Explorer", {}).get("Desktop")
+	size = sections.get(r"Software\Wine\Explorer\Desktops", {}).get(desktop_name)
+	return DesktopRegistrySnapshot(
+		user_reg=user_reg,
+		sha256=sha256_file(user_reg),
+		desktop_name=desktop_name,
+		selected_desktop=RegistryValue(selected is not None, selected),
+		desktop_size=RegistryValue(size is not None, size),
+	)
+
+
+def desktop_registry_restored(
+	before: DesktopRegistrySnapshot,
+	after: DesktopRegistrySnapshot,
+) -> bool:
+	return (
+		before.desktop_name == after.desktop_name
+		and before.selected_desktop == after.selected_desktop
+		and before.desktop_size == after.desktop_size
+	)
+
+
+def read_registry_string_values(path: Path) -> dict[str, dict[str, str]]:
+	sections: dict[str, dict[str, str]] = {}
+	current: dict[str, str] | None = None
+	with path.open("r", encoding="utf-8", errors="replace") as handle:
+		for raw in handle:
+			line = raw.rstrip("\r\n")
+			section = _SECTION_RE.match(line)
+			if section is not None:
+				name = section.group("name").replace(r"\\", "\\")
+				current = sections.setdefault(name, {})
+				continue
+			if current is None:
+				continue
+			match = _VALUE_RE.match(line)
+			if match is None:
+				continue
+			name = _decode_string(match.group("name"))
+			value_text = match.group("value")
+			if name is None or not value_text.startswith('"'):
+				continue
+			value = _decode_string(value_text)
+			if value is not None:
+				current[name] = value
+	return sections
+
+
+def _decode_string(value: str) -> str | None:
+	try:
+		result = ast.literal_eval(value)
+	except (SyntaxError, ValueError):
+		return None
+	return result if isinstance(result, str) else None