No need to use a QBuffer in DownloadJob

Summary:
QSslSocket is already a QIODevice so just use that.

Should fix the issue of transfering *big* files.

Unfortunately this seems to trigger a bug in KIO and CPU usage goes through the roof, so haven't really been able to test it does actually fix things.

Please don't merge/approve yet

Reviewers: apol, albertvaka, kdeconnect

Subscribers: #kde_connect

Differential Revision: https://phabricator.kde.org/D6039

core/backends/lan/downloadjob.cpp

@@ -31,17 +31,30 @@
 #include "lanlinkprovider.h"
 #include "core/core_debug.h"
 
+class QQSslSocket : public QSslSocket
+{
+private:
+    // Workaround Qt bug https://codereview.qt-project.org/#/c/195723/
+    qint64 readData(char *data, qint64 maxSize) override {
+        qint64 res = QSslSocket::readData(data, maxSize);
+        if (res == 0 && encryptedBytesAvailable() == 0 && state() != ConnectedState) {
+            return maxSize ? qint64(-1) : qint64(0);
+        } else {
+            return res;
+        }
+    }
+};
+
 DownloadJob::DownloadJob(const QHostAddress &address, const QVariantMap &transferInfo)
     : KJob()
     , mAddress(address)
     , mPort(transferInfo[QStringLiteral("port")].toInt())
-    , mSocket(new QSslSocket)
-    , mBuffer(new QBuffer)
+    , mSocket(new QQSslSocket)
 {
     LanLinkProvider::configureSslSocket(mSocket.data(), transferInfo.value(QStringLiteral("deviceId")).toString(), true);
 
     connect(mSocket.data(), SIGNAL(error(QAbstractSocket::SocketError)), this, SLOT(socketFailed(QAbstractSocket::SocketError)));
-//     connect(mSocket.data(), &QAbstractSocket::stateChanged, [](QAbstractSocket::SocketState state){ qDebug() << "statechange" << state; });
+    connect(mSocket.data(), &QAbstractSocket::connected, this, &DownloadJob::socketConnected);
 }
 
 DownloadJob::~DownloadJob()
@@ -54,26 +67,22 @@ void DownloadJob::start()
     //TODO: Timeout?
     // Cannot use read only, might be due to ssl handshake, getting QIODevice::ReadOnly error and no connection
     mSocket->connectToHostEncrypted(mAddress.toString(), mPort, QIODevice::ReadWrite);
-
-    bool b = mBuffer->open(QBuffer::ReadWrite);
-    Q_ASSERT(b);
 }
 
 void DownloadJob::socketFailed(QAbstractSocket::SocketError error)
 {
-    if (error != QAbstractSocket::RemoteHostClosedError) { //remote host closes when finishes
-        qWarning(KDECONNECT_CORE) << "error..." << mSocket->errorString();
-        setError(error + 1);
-        setErrorText(mSocket->errorString());
-    } else {
-        auto ba = mSocket->readAll();
-        mBuffer->write(ba);
-        mBuffer->seek(0);
-    }
+    qWarning() << "error..." << (error == QAbstractSocket::RemoteHostClosedError) << mSocket->errorString();
+    setError(error + 1);
+    setErrorText(mSocket->errorString());
     emitResult();
 }
 
 QSharedPointer<QIODevice> DownloadJob::getPayload()
 {
-    return mBuffer.staticCast<QIODevice>();
+    return mSocket.staticCast<QIODevice>();
+}
+
+void DownloadJob::socketConnected()
+{
+    emitResult();
 }

core/backends/lan/downloadjob.h

@@ -47,11 +47,10 @@ private:
     QHostAddress mAddress;
     qint16 mPort;
     QSharedPointer<QSslSocket> mSocket;
-    QSharedPointer<QBuffer> mBuffer;
 
 private Q_SLOTS:
     void socketFailed(QAbstractSocket::SocketError error);
-
+    void socketConnected();
 };
 
 #endif // UPLOADJOB_H

core/filetransferjob.cpp

@@ -79,6 +79,10 @@ void FileTransferJob::doStart()
 
 void FileTransferJob::startTransfer()
 {
+    // Don't put each ready read
+    if (mTimer.isValid())
+        return;
+
     setProcessedAmount(Bytes, 0);
     mTimer.start();
     description(this, i18n("Receiving file over KDE Connect"),