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ptdiag/filesystem.py

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+"""Read-only filesystem and hash verification helpers."""
+
+from __future__ import annotations
+
+from dataclasses import asdict, dataclass
+from hashlib import sha256
+from pathlib import Path
+from typing import Mapping
+
+
+KNOWN_GAME_HASHES: dict[str, str] = {
+	"Game.exe": "3cc0980aac0f65b379ff340ec61750498fb9f620fb6c88aa66281e8ab27023a5",
+	"game.dll": "7ea85b19f452962a39c91f967cad22495f066b2d52e8ac37f4e234463d5c4f09",
+	"gamese.exe": "c3443e50a93c6c778eff456122c351e5c7d2c1ceaea50e5a650bffe846a05c87",
+	"gamese.dll": "0ae6822f5f347f04bd2b0dc947f0286089c711c84703e110f6f8fc6e0d626131",
+}
+
+
+@dataclass(frozen=True)
+class HashVerification:
+	path: Path
+	expected_sha256: str
+	actual_sha256: str | None
+	ok: bool
+	error: str | None = None
+
+	def to_dict(self) -> dict[str, str | bool | None]:
+		data = asdict(self)
+		data["path"] = str(self.path)
+		return data
+
+
+def sha256_file(path: Path, chunk_size: int = 1024 * 1024) -> str:
+	if chunk_size <= 0:
+		raise ValueError("chunk_size must be positive")
+	digest = sha256()
+	with path.open("rb") as handle:
+		for chunk in iter(lambda: handle.read(chunk_size), b""):
+			digest.update(chunk)
+	return digest.hexdigest()
+
+
+def verify_file_hash(path: Path, expected_sha256: str) -> HashVerification:
+	expected = expected_sha256.casefold()
+	try:
+		actual = sha256_file(path)
+	except (OSError, ValueError) as exc:
+		return HashVerification(path, expected, None, False, str(exc))
+	return HashVerification(path, expected, actual, actual == expected)
+
+
+def verify_hashes(expected: Mapping[Path, str]) -> list[HashVerification]:
+	return [verify_file_hash(path, digest) for path, digest in expected.items()]
+
+
+def verify_known_game_hashes(live_game: Path) -> list[HashVerification]:
+	expected = {live_game / name: digest for name, digest in KNOWN_GAME_HASHES.items()}
+	return verify_hashes(expected)
+