ImportManager::uploadChunk

public function uploadChunk(Entry $entry)
{
	$tmpFile = CTempFile::getFileName(uniqid('_wd', true));
	checkDirPath($tmpFile);

	$fileData = new DocumentFileData;
	$fileData->setId($entry->getServiceObjectId());
	$fileData->setMimeType($entry->getMimeType());
	$fileData->setSrc($tmpFile);

	$chunkSize = self::CHUNK_SIZE;
	$downloadedContentSize = $entry->getDownloadedContentSize();
	$contentSize = $entry->getContentSize();

	if($contentSize == 0 && $this->documentHandler instanceof DocumentGoogleHandler)
	{
		return $this->uploadEmptyFileFromGoogle($entry, $fileData);
	}

	if($contentSize - $downloadedContentSize < $chunkSize)
	{
		$chunkSize = $contentSize - $downloadedContentSize;
	}

	$startRange = $downloadedContentSize;
	if(!$this->documentHandler->downloadPartFile($fileData, $startRange, $chunkSize))
	{
		$this->errorCollection->add($this->documentHandler->getErrors());
		return false;
	}

	$token = null;
	if($entry->getTmpFile() && $entry->getTmpFile()->getToken())
	{
		//todo it's strange, fix it
		$token = $entry->getTmpFile()->getToken();
	}

	$uploadFileManager = $this->uploadFileManager;
	$uploadFileManager
		->setFileSize($contentSize)
		->setEntry($entry)
		->setToken($token)
		->setContentRange(array($startRange, $startRange + $chunkSize - 1))
	;
	$tmpFileArray = CFile::makeFileArray($tmpFile);
	if(!$uploadFileManager->upload($fileData->getId(), $tmpFileArray))
	{
		$this->errorCollection->add($uploadFileManager->getErrors());
		return false;
	}
	if($token === null)
	{
		$entry->linkTmpFile(TmpFile::load(array('=TOKEN' => $uploadFileManager->getToken())));
	}

	return $entry->increaseDownloadedContentSize($chunkSize);
}