static int message_copy_to_user()

in nsm-driver/nsm.c [162:191]

• 17 lines of code
• 6 McCabe index (conditional complexity)

static int message_copy_to_user(struct nsm_message *user_msg,
	struct nsm_kernel_message *kern_msg)
{
	struct nsm_message shallow_copy;

	if (!kern_msg || !user_msg)
		return -EINVAL;

	/*
	 * First, do a shallow copy of the user-space message. This is needed in
	 * order to get the request block data, which we do not need to copy but
	 * must preserve in the message sent back to user-space.
	 */
	if (copy_from_user(&shallow_copy, user_msg, sizeof(shallow_copy)) != 0)
		return -EINVAL;

	/* Do not exceed the capacity of the user-provided response buffer */
	shallow_copy.response.iov_len = kern_msg->response.iov_len;

	/* Only the response content must be copied back to user-space */
	if (copy_to_user(shallow_copy.response.iov_base,
		kern_msg->response.iov_base,
		shallow_copy.response.iov_len) != 0)
		return -EINVAL;

	if (copy_to_user(user_msg, &shallow_copy, sizeof(shallow_copy)) != 0)
		return -EFAULT;

	return 0;
}