1# Copyright 2021 The Pigweed Authors 2# 3# Licensed under the Apache License, Version 2.0 (the "License"); you may not 4# use this file except in compliance with the License. You may obtain a copy of 5# the License at 6# 7# https://www.apache.org/licenses/LICENSE-2.0 8# 9# Unless required by applicable law or agreed to in writing, software 10# distributed under the License is distributed on an "AS IS" BASIS, WITHOUT 11# WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the 12# License for the specific language governing permissions and limitations under 13# the License. 14"""Generates nanopb_pb2.py by importing the Nanopb proto module. 15 16The Nanopb repository generates nanopb_pb2.py dynamically when its Python 17package is imported if it does not exist. If multiple processes try to use 18Nanopb to compile simultaneously on a clean build, they can interfere with each 19other. One process might rewrite nanopb_pb2.py as another process is trying to 20access it, resulting in import errors. 21 22This script imports the Nanopb module so that nanopb_pb2.py is generated if it 23doesn't exist. All Nanopb proto compilation targets depend on this script so 24that nanopb_pb2.py is guaranteed to exist before they need it. 25""" 26 27import argparse 28import importlib.util 29from pathlib import Path 30import sys 31 32 33def generate_nanopb_proto(root: Path) -> None: 34 sys.path.append(str(root / 'generator')) 35 36 spec = importlib.util.spec_from_file_location( 37 'proto', root / 'generator' / 'proto' / '__init__.py' 38 ) 39 assert spec is not None 40 proto_module = importlib.util.module_from_spec(spec) 41 spec.loader.exec_module(proto_module) # type: ignore[union-attr] 42 43 44def _parse_args() -> argparse.Namespace: 45 parser = argparse.ArgumentParser(description=__doc__) 46 parser.add_argument('root', type=Path, help='Nanopb root') 47 return parser.parse_args() 48 49 50if __name__ == '__main__': 51 generate_nanopb_proto(**vars(_parse_args())) 52