Function is_valid_subpath

common/hf-cache.cpp:166–175

}

static bool is_valid_subpath(const fs::path & path, const fs::path & subpath) {
    if (subpath.is_absolute()) {
        return false; // never do a / b with b absolute
    }
    auto b = fs::absolute(path).lexically_normal();
    auto t = (b / subpath).lexically_normal();
    auto [b_end, _] = std::mismatch(b.begin(), b.end(), t.begin(), t.end());

    return b_end == b.end();
}

static void safe_write_file(const fs::path & path, const std::string & data) {
    fs::path path_tmp = path.string() + ".tmp";