How to manage zip file

[mrdebug]

Hi. I have to manage a zip file (not gzip, just zip). Can somenone suggest me a way to do it (on both Linux and Windows)? qCompress and qUncompress does not work.

Regards.

[jsulm]

@mrdebug http://www.antonioborondo.com/2014/10/22/zipping-and-unzipping-files-with-qt/

[VRonin]

The only answer is zlib, you just need to decide the flavour

• QuaZIP (handles only .zip, wrapper around zlib)
• KArchive (supports multiple compression formats, for zip it's a wrapper on zlib)
• zlib if you don't mind C then you can use directly the reference library for zip files

I personally use KArchive because it's already conveniently wrapped in a Qt style and it can rely on the support of KDE

[mrdebug]

Hi. I'm trying to use quazip.
I have built quazip package without problem. When I try to run

JlCompress::extractDir("a.zip", ".");

the probgram goes to crash.

.pro

windows {
    INCLUDEPATH += C:/Users/Denis/git/ControlloAccessi/quazip-0.7.2
    INCLUDEPATH += C:/Users/Denis/git/ControlloAccessi/zlib128-dll/include
    LIBS += C:/Users/Denis/git/ControlloAccessi/quazip-0.7.2/quazip/release/quazip.lib
}

main.cpp

#include "quazip/quazip.h"
#include "QFile"
#include "QDebug"

#include <quazip/JlCompress.h>

MainWindow::MainWindow(QWidget *parent) : QMainWindow(parent), ui(new Ui::MainWindow) {
    ui->setupUi(this);
    JlCompress::extractDir("a.zip", "b");
}

[jsulm]

@mrdebug Did you try to debug to see what happens? Is it SIGSEGV or something else? Any error messages?

[VRonin]

@mrdebug said in How to manage zip file:

When I try to run

You are linking to the release version of quazip so make sure you run the release version of your app.

change LIBS += C:/Users/Denis/git/ControlloAccessi/quazip-0.7.2/quazip/release/quazip.lib into

CONFIG(debug, debug|release) {
    LIBS += -L"C:/Users/Denis/git/ControlloAccessi/quazip-0.7.2/quazip/debug"
    LIBS += -lquazipd
}else {
    LIBS += -L"C:/Users/Denis/git/ControlloAccessi/quazip-0.7.2/quazip/release"
    LIBS += -lquazip
}

Also make sure you make both Quazip.dll and zlib.dll (if you did not compile it as static) available at runtime

[mrdebug]

Sorry. I have missed the required dlls.
Is there a way to unzip a zip stream, from a QByteArray without to store it to a file before?

[VRonin]

yes with http://quazip.sourceforge.net/classQuaZip.html#ae52ebadd5ce64cdb49d7e198904b0b8c
create a QDataStream operating on the QByteArary and then pass QDataStream::device() to that constructor.

On the other hand, I'm not sure what you are trying to do but you might not need QuaZip at all, have a look at http://doc.qt.io/qt-5/qbytearray.html#qCompress and below

[mrdebug]

Someting like this?

                    QDataStream BufferIn(&Source, QIODevice::ReadOnly);
                    QuaZipFile quaZip(BufferIn.device());
                    qDebug() << quaZip.open(QIODevice::ReadOnly);

returns false...

[VRonin]

QuaZipFile represents a file inside a zip file, not a zip file in itself. the constructor you are calling is this one: http://quazip.sourceforge.net/classQuaZipFile.html#a1349ad27f1947bc3e346d83dbf9586c4 use QuaZip instead.

P.S.
QDataStream BufferIn(&Source, QIODevice::ReadOnly); is the same as QDataStream BufferIn(Source);

[mrdebug]

After many tries I can't unzip something without to use a file.
These lines of code

                        QDataStream BufferIn(&QBABufferOut, QIODevice::ReadOnly);
                        QuaZip quaZip(BufferIn.device());

does not seem to work.

[SGaist]

Hi,

What do you have in QBABufferOut ?
Are you sure it's opened correctly ?
Why do you need BufferIn for ?

And most important, what do you mean by does not seem to work? That's to vague to help you.

[mrdebug]

Please have a look at this sequence:

                            QuaZipFile quaZip(QBABufferOut);                // (rapresents a zip archivie in ram).
                            if (quaZip.open(QIODevice::ReadOnly)) {         // QIODevice::ReadOnly or someting else
                                qDebug() << "ok";
                            } else qDebug() << "error";                     // always error!!!!!!!!!!!!

[VRonin]

You have to open the QuaZip for decompression first:

    QBuffer storageBuff(&QBABufferOut);
    QuaZip zip(&storageBuff);
    if (!zip.open(QuaZip::mdUnzip))
        qDebug() << "error";
    QuaZipFile file(&zip);
    for (bool f = zip.goToFirstFile(); f; f = zip.goToNextFile()) {
        QuaZipFileInfo fileInfo;
        file.getFileInfo(&fileInfo);
        qDebug() << fileInfo.name;
        file.open(QIODevice::ReadOnly);
        
        qDebug() << "Content: " << file.readAll().toBase64();
        file.close();
    }
    zip.close();

P.S.

// (rapresents a zip archivie in ram).

No it doesn't. As mentioned before QuaZipFile represent a file inside a zip archive, not the archive itself

[mrdebug]

It works perfectly.
Many thanks.

[SPlatten]

@VRonin said in How to manage zip file:

QuaZIP

Is there a license associated with the use of this? As I have a need for compressing large amounts of binary data that I need to transmit to remote clients.

[jsulm]

@SPlatten said in How to manage zip file:

Is there a license associated with the use of this?

https://github.com/stachenov/quazip

[SPlatten]

Thank you,

[artwaw]

@SPlatten if both ends are in your software I'd suggest agains using 3rd party library. qCompress and qUncompress work just fine in that regard. My usual approach is to supply a header (using QDataStream) with checksum and whatever else is needed, then stream to it output from compression routine. Works sufficiently well, eliminates the need for another dependency.

[SPlatten]

@artwaw , Thank you, I will have a look.