Function fill_random_getrandom

src/unique_path.cpp:174–204

Fills buffer with cryptographically random data obtained from getrandom()

//! Fills buffer with cryptographically random data obtained from getrandom()
int fill_random_getrandom(void* buf, std::size_t len)
{
    std::size_t bytes_read = 0u;
    while (bytes_read < len)
    {
#if defined(BOOST_FILESYSTEM_HAS_GETRANDOM)
        ssize_t n = ::getrandom(buf, len - bytes_read, 0u);
#else
        ssize_t n = ::syscall(SYS_getrandom, buf, len - bytes_read, 0u);
#endif
        if (BOOST_UNLIKELY(n < 0))
        {
            const int err = errno;
            if (err == EINTR)
                continue;

            if (err == ENOSYS && bytes_read == 0u)
            {
                filesystem::detail::atomic_store_relaxed(fill_random, &fill_random_dev_random);
                return fill_random_dev_random(buf, len);
            }

            return err;
        }

        bytes_read += n;
        buf = static_cast< char* >(buf) + n;
    }

    return 0;
}

#endif // defined(BOOST_FILESYSTEM_HAS_GETRANDOM) || defined(BOOST_FILESYSTEM_HAS_GETRANDOM_SYSCALL)