tools/check_license_headers.py

#!/usr/bin/env python3

#
# Licensed to the Apache Software Foundation (ASF) under one or more
# contributor license agreements.  See the NOTICE file distributed with
# this work for additional information regarding copyright ownership.
# The ASF licenses this file to You under the Apache License, Version 2.0
# (the "License"); you may not use this file except in compliance with
# the License.  You may obtain a copy of the License at
#
#    http://www.apache.org/licenses/LICENSE-2.0
#
# Unless required by applicable law or agreed to in writing, software
# distributed under the License is distributed on an "AS IS" BASIS,
# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
# See the License for the specific language governing permissions and
# limitations under the License.
#

"""Validate ASF license headers on tracked text files."""

from __future__ import annotations

import subprocess
import sys
from pathlib import Path


ASF_HEADER_TOKEN = "Licensed to the Apache Software Foundation"

EXEMPT_FILES = {
    "Cargo.lock",
    # Generated dependency license report. CI verifies it against cargo-deny output.
    "DEPENDENCIES.rust.tsv",
    "LICENSE",
    "NOTICE",
    # Golden test data; adding comments changes the fixture format.
    "core/tests/golden/storage_v1_envelope.hex",
}


def repo_root() -> Path:
    return Path(
        subprocess.check_output(["git", "rev-parse", "--show-toplevel"], text=True).strip()
    )


def tracked_files(root: Path) -> list[str]:
    output = subprocess.check_output(["git", "-C", str(root), "ls-files"], text=True)
    return output.splitlines()


def is_text_file(path: Path) -> bool:
    return b"\0" not in path.read_bytes()


def has_asf_header(path: Path) -> bool:
    lines = path.read_text(encoding="utf-8", errors="replace").splitlines()
    return ASF_HEADER_TOKEN in "\n".join(lines[:80])


def main() -> int:
    root = repo_root()
    missing = []

    for file_name in tracked_files(root):
        if file_name in EXEMPT_FILES:
            continue

        path = root / file_name
        if not path.is_file() or not is_text_file(path):
            continue

        if not has_asf_header(path):
            missing.append(file_name)

    if missing:
        print("Files missing ASF license headers:", file=sys.stderr)
        for file_name in missing:
            print(f"  {file_name}", file=sys.stderr)
        return 1

    print("All tracked text files have ASF license headers or are explicitly exempt.")
    return 0


if __name__ == "__main__":
    sys.exit(main())