DocumentSessionCheck::onBeforeAction

public function onBeforeAction(Event $event)
{
	foreach ($this->getAction()->getArguments() as $argument)
	{
		if (!($argument instanceof DocumentSession))
		{
			continue;
		}

		$documentSession = $argument;

		$currentUserId = $this->getAction()->getCurrentUser()->getId();
		$currentUserId = $currentUserId? (int)$currentUserId : null;

		$isGuestSession = GuestUser::isGuestUserId($documentSession->getUserId()) && !$currentUserId;
		if (!$isGuestSession && $this->ownerCheck)
		{
			if ($currentUserId === null || !$documentSession->belongsToUser($currentUserId))
			{
				$this->addError(new Error('Could not operate by session from another user.'));

				return new EventResult(EventResult::ERROR, null, null, $this);
			}
		}
		if ($this->checkHash)
		{
			$hash = ($this->getHashValue)();
			if ($documentSession->getExternalHash() !== $hash)
			{
				$this->addError(new Error('Invalid document session id.'));

				return new EventResult(EventResult::ERROR, null, null, $this);
			}
		}
		if (!$isGuestSession && $this->strictCheckRight)
		{
			if ($documentSession->isView() && !$documentSession->canUserRead($this->getAction()->getCurrentUser()))
			{
				$this->addError(new Error('Could not read session.'));
			}
			if ($documentSession->isEdit() && !$documentSession->canUserEdit($this->getAction()->getCurrentUser()))
			{
				$this->addError(new Error('Could not edit document by session.'));
			}

			if ($this->getErrors())
			{
				return new EventResult(EventResult::ERROR, null, null, $this);
			}
		}
	}

	return null;
}