Seeking Help on Debugging QIODevice Issue

ModelTech

Perhaps a long shot, but I need some hits to help debugging a QIODevice issue that I experience. I am using the OPC Package component of QtOfficeOpenXml. The QtOfficeOpenXml::Opc::PackagePart returns a QIODevice when calling getDevice(). I need to process the content of this QIODevice by another library that requires using a concrete file. Hence, I copy the content of the QIODevice to a QTemporaryFile with the following code, where Device is the QIODevice of originating from calling QtOfficeOpenXml::Opc::PackagePart::getDevice()

    QDataStream InStream(Device);
    TempFile = new QTemporaryFile();
    TempFile->open();
    QString TempName = TempFile->fileName();
    QDataStream OutStream(TempFile);
    const int BlockSize = 1024;
    char Block[BlockSize];
    int Length = 0;
    while ((Length = InStream.readRawData(Block, BlockSize)) > 0)
        OutStream.writeRawData(Block, Length);
    TempFile->flush();
    TempFile->close();

The above code does work in most cases, but in some cases, I experience that QDataStream::readRawData returns a Length of 0, while the content is really not empty. I have added some tests such as checking with atEnd and using seek(0) to make sure the read pointer is at the beginning, but all that doesn't show signs of identifying a problem that would cause QDataStream::readRawData to return a Length of 0. Would anyone have more hits on how I could debug the problem further? Is there perhaps a way to inspect the content of the QIODevice in QtCreator's Debugger view? Any suggestions are appreciated :)

jsulm

@ModelTech Did you print https://doc.qt.io/qt-6/qiodevice.html#errorString before using Device?
There are also:

ModelTech

@jsulm Thanks for those ideas :)

I have tried the following:

    bool Test1 = Device->isOpen();
    bool Test2 = Device->isReadable();
    bool Test3 = Device->atEnd();
    bool Test4 = Device->isSequential();
    qint64 Test5 = Device->pos();
    QString Test6 = Device->errorString();

In both cases (i.e., where the first evaluation of Length in the condition of the while loop is larger than 0 and equal to 0, while it should be larger than 0 in both cases), I got:

    Test1 -> true
    Test2 -> true
    Test3 -> false
    Test4 -> false
    Test5 -> 0;
    Test6 -> "Unknown Error"

ModelTech

This post is deleted!

ModelTech

Ok. After trying lots of things, I found a bypass to the problem by using the QtOfficeOpenXml library in a slightly different way...