Added controller for the native world helper.

ptlinux/world_fix.py

@@ -0,0 +1,66 @@
+"""Exact-profile selection for the post-login V21 world-transition helper."""
+
+from __future__ import annotations
+
+import hashlib
+from pathlib import Path
+
+
+V21_BINARY_HASHES = {
+	"Game.exe": "2bc3edd26c5f6d7ae9bbdc23967c5aefd374bdf934fcdfa2ed42c6442e550837",
+	"game.dll": "4b4e5c28e2bfdaa8d36c8341fad27becfd03faf63aa8ea874f5d43c5b1961868",
+}
+WORLD_FIX_HELPER_FILENAME = "pt-world-fix.exe"
+# Filled from the reproducible stripped PE after the native helper is built.
+WORLD_FIX_HELPER_SHA256 = (
+	"d5bdf655f62dae429eff627cf8960f670ec59c12a9759dcd14342786f53e4019"
+)
+
+
+class WorldFixError(RuntimeError):
+	"""Raised when an exact client needs a missing or untrusted helper."""
+
+
+def packaged_world_fix_helper() -> Path:
+	return Path(__file__).resolve().parent / "native" / WORLD_FIX_HELPER_FILENAME
+
+
+def resolve_world_fix_helper(
+	game_directory: Path,
+	*,
+	helper: Path | None = None,
+) -> Path | None:
+	"""Return the verified helper only for the exact publisher V21 pair."""
+
+	game = game_directory.expanduser().resolve(strict=False)
+	hashes = {
+		name: _sha256(game / name)
+		for name in V21_BINARY_HASHES
+		if (game / name).is_file()
+	}
+	if hashes != V21_BINARY_HASHES:
+		return None
+	requested = packaged_world_fix_helper() if helper is None else helper.expanduser()
+	if requested.is_symlink():
+		raise WorldFixError(
+			"the post-login world-fix helper must not be a symbolic link"
+		)
+	candidate = requested.resolve()
+	if not candidate.is_file():
+		raise WorldFixError(
+			"the verified post-login world-fix helper is missing; reinstall the launcher"
+		)
+	digest = _sha256(candidate)
+	if digest != WORLD_FIX_HELPER_SHA256:
+		raise WorldFixError(
+			"the post-login world-fix helper failed its launcher integrity check"
+		)
+	return candidate
+
+
+def _sha256(path: Path) -> str:
+	digest = hashlib.sha256()
+	with path.open("rb") as handle:
+		for chunk in iter(lambda: handle.read(1024 * 1024), b""):
+			digest.update(chunk)
+	return digest.hexdigest()