Function sys_getrandom

components/lwp/lwp_syscall.c:8401–8465

* @brief Get random data from the kernel's random number generator. * * This function retrieves cryptographically secure random data from the kernel's random number generator * and stores it in the buffer provided by the user. The data can be used for cryptographic operations or * other applications requiring randomization. * * @param[out] buf A pointer to the buffer where the random dat

 * @see sys_random(), sys_getentropy()
 */
sysret_t sys_getrandom(void *buf, size_t buflen, unsigned int flags)
{
    int ret = -1;
    int count = 0;
    void *kmem = RT_NULL;
    rt_device_t rd_dev = RT_NULL;

    if (flags & GRND_RANDOM)
        rd_dev = rt_device_find("random");
    else
        rd_dev = rt_device_find("urandom");

    if (rd_dev == RT_NULL)
    {
        return -EFAULT;
    }

    if (rt_device_open(rd_dev, RT_DEVICE_OFLAG_RDONLY) != RT_EOK)
    {
        return -EFAULT;
    }

    if (!lwp_user_accessable(buf, buflen))
    {
        rt_device_close(rd_dev);
        return -EFAULT;
    }

#ifdef ARCH_MM_MMU
    kmem = kmem_get(buflen);
    if (!kmem)
    {
        rt_device_close(rd_dev);
        return -ENOMEM;
    }

    while (count < buflen)
    {
        ret = rt_device_read(rd_dev, count, (char *)kmem + count, buflen - count);
        if (ret <= 0)
            break;
        count += ret;
    }
    rt_device_close(rd_dev);

    ret = count;
    if (count > 0)
    {
        ret = lwp_put_to_user(buf, kmem, count);
    }
    kmem_put(kmem);
#else
    while (count < buflen)
    {
        ret = rt_device_read(rd_dev, count, (char *)kmem + count, buflen - count);
        if (ret <= 0)
            break;
        count += ret;