从QLocalSocket读取的字节数超过2048

我在从QLocalSocket读取超过2048个字节时遇到问题。这是我的服务器端代码：

clientConnection->flush();  // <-- clientConnection is a QLocalSocket
QByteArray block;
QDataStream out(&block, QIODevice::WriteOnly);
out.setVersion(QDataStream::Qt_5_0);
out << (quint16)message.size() << message;  // <--- message is a QString
qint64 c = clientConnection->write(block);
clientConnection->waitForBytesWritten();
if(c == -1)
    qDebug() << "ERROR:" << clientConnection->errorString();
clientConnection->flush();

这就是我读取客户端数据的方式：

QDataStream in(sock);  // <--- sock is a QLocalSocket
in.setVersion(QDataStream::Qt_5_0);
while(sock->bytesAvailable() < (int)sizeof(quint16)){
    sock->waitForReadyRead();
}
in >> bytes_to_read; // <--- quint16
while(sock->bytesAvailable() < (int)bytes_to_read){
    sock->waitForReadyRead();
}
in >> received_message;

客户端代码连接到readyRead信号，并且在第一次调用插槽后断开连接。

为什么我只能读取2048字节？

===编辑===

在peppe的回复之后，我更新了我的代码。以下是它现在的样子：

服务器端代码：

clientConnection->flush();
QByteArray block;
QDataStream out(&block, QIODevice::WriteOnly);
out.setVersion(QDataStream::Qt_5_0);
out << (quint16)0;
out << message;
out.device()->seek(0);
out << (quint16)(block.size() - sizeof(quint16));
qDebug() << "Bytes client should read" << (quint16)(block.size() - sizeof(quint16));
qint64 c = clientConnection->write(block);
clientConnection->waitForBytesWritten();

客户端代码：

QDataStream in(sock);
in.setVersion(QDataStream::Qt_5_0);
while(sock->bytesAvailable() < sizeof(quint16)){
    sock->waitForReadyRead();
}
quint16 btr;
in >> btr;
qDebug() << "Need to read" << btr << "and we have" << sock->bytesAvailable() << "in sock";
while(sock->bytesAvailable() < btr){
    sock->waitForReadyRead();
}
in >> received_message;
qDebug() << received_message;

我仍然无法读取更多数据。