tools/bazel/bazel_utils.py

# Copyright 2026 The Pigweed Authors
#
# Licensed 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
#
#     https://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.
"""Common Bazel utilities for conversion scripts."""

from pathlib import Path
import subprocess


def find_workspace_root(start_path: Path) -> Path:
    """Finds the Bazel workspace root by looking for WORKSPACE or MODULE.bazel."""
    curr = start_path.resolve()
    while curr != curr.parent:
        if (
            (curr / "WORKSPACE").exists()
            or (curr / "MODULE.bazel").exists()
            or (curr / ".git").exists()
        ):
            return curr
        curr = curr.parent
    # Fallback to CWD
    return Path.cwd().resolve()


def get_bazel_package_prefix(output_dir: Path) -> str:
    """Determines the Bazel package prefix for the output directory.

    Returns something like '//third_party/zephyr' or '//'.
    """
    workspace_root = find_workspace_root(output_dir)
    abs_output_dir = output_dir.resolve()
    try:
        rel_path = abs_output_dir.relative_to(workspace_root)
        if str(rel_path) == ".":
            return "//"

        return f"//{rel_path}"
    except ValueError:
        print(
            f"Warning: Output directory {abs_output_dir} is not under workspace root {workspace_root}."
        )
        return ""


def expose_files(build_file: Path, files: list[str], comment: str = ""):
    """Appends exports_files to a BUILD.bazel file."""
    if not build_file.exists():
        print(f"Warning: {build_file} not found, skipping.")
        return

    content = "\n"
    if comment:
        content += f"# {comment}\n"
    files_str = ", ".join(f'"{f}"' for f in files)
    content += f'exports_files([{files_str}], visibility = ["//visibility:public"])\n'

    with open(build_file, "a", encoding="utf-8") as f:
        f.write(content)
    print(f"Exposed {files} in {build_file}")


def run_buildozer(instructions: list[str], target: str) -> bool:
    """Runs buildozer with the given instructions on the target."""
    cmd = ["buildozer"] + instructions + [target]
    try:
        result = subprocess.run(
            cmd, stdout=subprocess.PIPE, stderr=subprocess.PIPE, text=True
        )
        if result.returncode not in (0, 3):
            print(f"Error running buildozer: {result.stderr.strip()}")
            print(f"Command was: {' '.join(cmd)}")
            return False
        elif result.returncode == 0:
            print(f"Buildozer: Applied changes to {target}")
        elif result.returncode == 3:
            print(f"Buildozer: No changes needed for {target}")
        return True
    except FileNotFoundError:
        print(
            "Error: 'buildozer' command not found. Please install buildozer to apply all fixups."
        )
        print(f"Failed to apply to {target}: {instructions}")
        return False