1 files changed, 37 insertions, 4 deletions
diff --git a/third_party/nanopb/generate_nanopb_proto.py b/third_party/nanopb/generate_nanopb_proto.py
index 2934d0635..fc83df024 100644
--- a/third_party/nanopb/generate_nanopb_proto.py
+++ b/third_party/nanopb/generate_nanopb_proto.py
@@ -27,14 +27,28 @@ that nanopb_pb2.py is guaranteed to exist before they need it.
 import argparse
 import importlib.util
 from pathlib import Path
+import os
 import sys
 
 
-def generate_nanopb_proto(root: Path) -> None:
-    sys.path.append(str(root / 'generator'))
+def generate_nanopb_proto(
+    nanopb_root: Path, protoc_binary: Path, aggressive_regen: bool
+) -> None:
+    generated_nanopb_pb2 = nanopb_root / 'generator' / 'proto' / 'nanopb_pb2.py'
+
+    # If protoc was updated, ensure the file is regenerated.
+    if generated_nanopb_pb2.is_file():
+        if (
+            aggressive_regen
+            or protoc_binary.stat().st_mtime
+            > generated_nanopb_pb2.stat().st_mtime
+        ):
+            os.remove(generated_nanopb_pb2)
+
+    sys.path.append(str(nanopb_root / 'generator'))
 
     spec = importlib.util.spec_from_file_location(
-        'proto', root / 'generator' / 'proto' / '__init__.py'
+        'proto', nanopb_root / 'generator' / 'proto' / '__init__.py'
     )
     assert spec is not None
     proto_module = importlib.util.module_from_spec(spec)
@@ -43,7 +57,26 @@ def generate_nanopb_proto(root: Path) -> None:
 
 def _parse_args() -> argparse.Namespace:
     parser = argparse.ArgumentParser(description=__doc__)
-    parser.add_argument('root', type=Path, help='Nanopb root')
+    parser.add_argument(
+        '--nanopb-root',
+        type=Path,
+        help='Nanopb root',
+    )
+    parser.add_argument(
+        '--protoc-binary',
+        type=Path,
+        help='Protoc binary path',
+    )
+    parser.add_argument(
+        '--aggressive-regen',
+        action="store_true",
+        default=False,
+        help=(
+            'If true, always regenerates nanopb_pb2.py when this script is '
+            'run. If this is false, the file is only regenerated when the '
+            'protoc binary is updated'
+        ),
+    )
     return parser.parse_args()