Merge "Use ReadFileToString() in GetHash()"

}

std::optional<std::string> GetHash(const std::string& path) {

    unique_fd fd(open(path.c_str(), O_RDONLY));

    char buf[4096];

    SHA256_CTX ctx;

    SHA256_Init(&ctx);

    while (true) {

        ssize_t n = TEMP_FAILURE_RETRY(read(fd.get(), buf, sizeof(buf)));

        if (n < 0) {

            PLOG(ERROR) << "Cannot read " << path;

    std::string content;

    if (!android::base::ReadFileToString(path, &content, true)) {

        PLOG(ERROR) << "Cannot access " << path;

        return std::nullopt;

    }

        if (n == 0) {

            break;

        }

        SHA256_Update(&ctx, buf, n);

    }

    SHA256_CTX ctx;

    SHA256_Init(&ctx);

    SHA256_Update(&ctx, content.c_str(), content.size());

    uint8_t out[32];

    SHA256_Final(out, &ctx);

    return ToHexString(out, sizeof(out));