Init

ptlinux/launcher_wrapper.py

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+"""Render the installed command wrapper with persistent application paths."""
+
+from __future__ import annotations
+
+import argparse
+import os
+from pathlib import Path
+import sys
+from typing import Sequence
+
+
+APP_ROOT_TOKEN = "@PTLINUX_APP_ROOT@"
+INSTALL_DIRECTORY_TOKEN = "@PTLINUX_INSTALL_DIR@"
+
+
+class LauncherWrapperError(ValueError):
+	"""Raised when a safe launcher wrapper cannot be rendered."""
+
+
+def quote_shell_word(value: str) -> str:
+	"""Quote one value as a literal POSIX shell word."""
+
+	if not value or any(character in value for character in ("\x00", "\n", "\r")):
+		raise LauncherWrapperError("launcher path contains invalid characters")
+	return "'" + value.replace("'", "'\"'\"'") + "'"
+
+
+def _absolute_directory(path: Path, label: str) -> Path:
+	directory = path.expanduser()
+	if not directory.is_absolute():
+		raise LauncherWrapperError(f"{label} must be absolute")
+	return directory
+
+
+def render_launcher_wrapper(
+	template: str,
+	app_root: Path,
+	install_directory: Path,
+) -> str:
+	"""Embed the selected install layout in one command-wrapper template."""
+
+	for token in (APP_ROOT_TOKEN, INSTALL_DIRECTORY_TOKEN):
+		if template.count(token) != 1:
+			raise LauncherWrapperError(
+				f"launcher template must contain exactly one {token} token"
+			)
+	application = _absolute_directory(app_root, "application directory")
+	installation = _absolute_directory(install_directory, "install directory")
+	if not any(
+		(candidate / "ptlinux").is_dir()
+		for candidate in (
+			application / "current",
+			application / "previous",
+			application,
+		)
+	):
+		raise LauncherWrapperError(f"application files are missing: {application}")
+	rendered = template.replace(APP_ROOT_TOKEN, quote_shell_word(str(application)))
+	rendered = rendered.replace(
+		INSTALL_DIRECTORY_TOKEN,
+		quote_shell_word(str(installation)),
+	)
+	return rendered if rendered.endswith("\n") else rendered + "\n"
+
+
+def install_launcher_wrapper(
+	template: Path,
+	app_root: Path,
+	install_directory: Path,
+	destination: Path,
+) -> None:
+	"""Render and atomically install one executable command wrapper."""
+
+	rendered = render_launcher_wrapper(
+		template.read_text(encoding="utf-8"),
+		app_root,
+		install_directory,
+	)
+	destination.parent.mkdir(parents=True, exist_ok=True)
+	temporary = destination.with_name(f".{destination.name}.{os.getpid()}.tmp")
+	try:
+		temporary.write_text(rendered, encoding="utf-8")
+		temporary.chmod(0o755)
+		temporary.replace(destination)
+	except BaseException:
+		temporary.unlink(missing_ok=True)
+		raise
+
+
+def main(argv: Sequence[str] | None = None) -> int:
+	parser = argparse.ArgumentParser(
+		description="install the PristonTale EU command wrapper"
+	)
+	parser.add_argument("template", type=Path)
+	parser.add_argument("app_root", type=Path)
+	parser.add_argument("install_directory", type=Path)
+	parser.add_argument("destination", type=Path)
+	arguments = parser.parse_args(argv)
+	try:
+		install_launcher_wrapper(
+			arguments.template,
+			arguments.app_root,
+			arguments.install_directory,
+			arguments.destination,
+		)
+	except (LauncherWrapperError, OSError) as exc:
+		print(f"Could not install command wrapper: {exc}", file=sys.stderr)
+		return 1
+	return 0
+
+
+if __name__ == "__main__":
+	raise SystemExit(main())