update-compile-commands-symlink

#!/usr/bin/env python3

# Copyright (C) 2024 Igalia S.L.
#
# Redistribution and use in source and binary forms, with or without
# modification, are permitted provided that the following conditions
# are met:
#
# 1.  Redistributions of source code must retain the above copyright
#     notice, this list of conditions and the following disclaimer.
# 2.  Redistributions in binary form must reproduce the above copyright
#     notice, this list of conditions and the following disclaimer in the
#     documentation and/or other materials provided with the distribution.
# 3.  Neither the name of Apple Inc. ("Apple") nor the names of
#     its contributors may be used to endorse or promote products derived
#     from this software without specific prior written permission.
#
# THIS SOFTWARE IS PROVIDED BY APPLE AND ITS CONTRIBUTORS "AS IS" AND ANY
# EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
# WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
# DISCLAIMED. IN NO EVENT SHALL APPLE OR ITS CONTRIBUTORS BE LIABLE FOR ANY
# DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
# (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
# LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND
# ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
# (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
# THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.

from __future__ import annotations
import argparse
import re
import os
import sys
from pathlib import Path
from typing import IO
from dataclasses import dataclass
from configparser import ConfigParser


@dataclass
class Config:
    candidates: list[str]

    @staticmethod
    def load(file: IO[str]) -> Config:
        parser = ConfigParser()
        parser.read_file(file)
        candidates_str = parser["update-compile-commands-symlink"]["candidates"]
        candidates = [
            line.strip()
            for line in candidates_str.splitlines()
            if line.strip() != ""
        ]
        return Config(candidates)


def update_symlink_with_path(symlink_path: Path, target_str: str):
    try:
        current_target = os.readlink(symlink_path)
        symlink_exists = True
    except FileNotFoundError:
        current_target = None
        symlink_exists = False

    if symlink_exists and current_target != target_str:
        os.remove(symlink_path)
    if not symlink_exists or current_target != target_str:
        os.symlink(target_str, symlink_path)


def update_symlink_from_candidates(symlink_path: Path, config_path: Path):
    with open(config_path, "r", encoding="utf-8") as f:
        config = Config.load(f)
    # Pick first candidate that exists.
    for candidate_str in config.candidates:
        candidate_str = os.path.expanduser(candidate_str)
        # Paths are resolved relative to the directory containing the candidates file.
        if Path(config_path.parent, candidate_str).exists():
            if sys.platform == "win32":
                # Windows requires backslashes for symlinks.
                candidate_str = candidate_str.replace("/", "\\")
            update_symlink_with_path(symlink_path, candidate_str)
            return
    print(f"update-compile-commands-symlink: Couldn't update {symlink_path}. "
        f"None of the candidates provided in {config_path} exist.",
        file=sys.stderr)


def main():
    parser = argparse.ArgumentParser("update-compile-commands-symlink")
    parser.add_argument("symlink_path", type=Path)
    parser.add_argument("config_file", type=Path)
    args = parser.parse_args()
    update_symlink_from_candidates(args.symlink_path, args.config_file)


if __name__ == "__main__":
    main()