Wrong donwloaded filesize in Qt 5.6 - c++

Question

I used a DownloadManager class like that but the problem is that for large file I have a wrong size 65536KB instead of 51328022 bytes. There are something wrong in the saveDisk method.
ps: I used Qt 5.6 cuz I need to run the app on Windows Vista & XP
bool DownloadManager::saveToDisk(const QString &filename, QIODevice *data)
{
LogManager* logmgr = LogManager::GetInstance();
FileManager* filemgr = FileManager::GetInstance();
QFileInfo fileinfo(filename);
QString dirpath = fileinfo.absoluteDir().absolutePath();
if (!filemgr->DirectoryIsPresent(dirpath))
{
if (!filemgr->CreateDirectory(dirpath)) {
logmgr->Log(LOG_LEVEL_ERROR, QString("cannot create directory (") + dirpath + ")");
}
}
QFile file(filename);
if (!file.open(QIODevice::WriteOnly)) {
const QString errorText = QString("Could not open ") + filename + QString(" for writing:") + file.errorString();
logmgr->Log(LOG_LEVEL_ERROR, errorText);
return false;
}
file.write(data->readAll());
file.close();
return true;
}
void DownloadManager::downloadFinished(QNetworkReply *reply)
{
LogManager* logmgr = LogManager::GetInstance();
if (m_currentDownloads.contains(reply))
{
QUrl url = reply->url();
if (reply->error() != QNetworkReply::NoError) {
m_nbFailedDownload++;
const QString errorText = QString("Download of ")+ url.toString() +" failed: " + reply->errorString() + " (" + QString::number(reply->error()) + ")";
logmgr->Log(LOG_LEVEL_ERROR, errorText);
} else {
m_nbSucceededDownload++;
QString filename = saveFileName(url);
if (saveToDisk(filename, reply))
{
const QString infoText = QString("Download of ") + url.toString() + " succeeded (saved to " + filename + ")";
logmgr->Log(LOG_LEVEL_INFO, infoText);
}
}
m_currentDownloads.removeAll(reply);
reply->deleteLater();
}
int total = m_nbTotalDownload == 0? 1:m_nbTotalDownload;
emit onProgress((m_nbFailedDownload + m_nbSucceededDownload) * 100 / total);
if (m_currentDownloads.isEmpty()){
logmgr->Log(LOG_LEVEL_INFO, "DownloadManager downloads finished");
emit onFinished();
}
}

Answer 1

You should call DownloadManager::saveToDisk by signal QNetworkReply::readyRead
void DownloadManager::onDownloadReadyRead( QNetworkReply *reply )
{
...
saveToDisk( filename, reply );
...
}
void DownloadManager::saveToDisk( QNetworkReply* reply )
{
...
file.write( reply->read( reply_->bytesAvailable() ) );
...
}

Answer 2

It's ok. I replaced this line :
file.write(data->readAll());
file.close();
return true;
by
ByteArray ba = data->readAll();
int nbTries = 99;
int n = ba.size();
int idx = 0;
while (n > 0 && nbTries > 0)
{
int ret = file.write(ba.data() + idx, std::min(16*1024, n));
if (ret > 0)
{
n -= ret;
idx += ret;
}
else
{
nbTries --;
}
}
file.close();
return nbTries > 0;
I wrote several chunks instead of one big