MemoryExtractor crashes or emits error

[g-fb]

Select your issue type: (check at least one)

• [x] Bug
• [ ] Question
• [ ] Suggestion
• [ ] Other (please describe):

Describe your issue: MemoryExtractor crashes or emits error even though the finished signal is emitted and the file names are printed by qDebug().

Ways to Reproduce the issue (optional): Here's a sample project, just run the commands in the readme and double click a file to run the memory extraction. When (QIODevice*)&archive is passed to MemoryExtractor constructor it crashes.

1  QIODevice::isOpen                              qiodevice.cpp               603  0x7ffff6deb9e4 
2  QArchive::ExtractorPrivate::openArchive        qarchiveextractor_p.cc      561  0x412857       
3  QArchive::ExtractorPrivate::start              qarchiveextractor_p.cc      374  0x4120e1       
4  QArchive::ExtractorPrivate::qt_static_metacall moc_qarchiveextractor_p.cpp 198  0x40ddf2       
5  QObject::event                                 qobject.cpp                 1314 0x7ffff6ee84ae 
6  QApplicationPrivate::notify_helper             qapplication.cpp            3632 0x7ffff7a6aa7f 
7  QCoreApplication::notifyInternal2              qcoreapplication.cpp        1064 0x7ffff6ebbe3a 
8  QCoreApplicationPrivate::sendPostedEvents      qcoreapplication.cpp        1821 0x7ffff6ebee77 
9  postEventSourceDispatch                        qeventdispatcher_glib.cpp   277  0x7ffff6f13d03 
10 g_main_dispatch                                gmain.c                     3381 0x7ffff5ba2e22 
11 g_main_context_dispatch                        gmain.c                     4099 0x7ffff5ba2e22 
12 g_main_context_iterate                         gmain.c                     4175 0x7ffff5ba31b8 
13 g_main_context_iteration                       gmain.c                     4240 0x7ffff5ba326f 
14 QEventDispatcherGlib::processEvents            qeventdispatcher_glib.cpp   423  0x7ffff6f13384 
15 QEventLoop::exec                               qflags.h                    69   0x7ffff6eba83b 
16 QCoreApplication::exec                         qflags.h                    121  0x7ffff6ec2b10 
17 main                                           main.cpp                    10   0x407f88       

When I pass archiveFile directly sometimes it works sometimes it gives an error

...
Filename::  "astrology-astronomy-body-of-water-2406397.jpg"
Filename::  "beautiful-flowers-flowers-white-flowers-2395252.jpg"
QFileDevice::seek: IODevice is not open
QFileDevice::seek: IODevice is not open
An error has occured :: "QArchive::ArchiveCorrupted"

[antony-jr]

I will look into this. What OS are you in and what archive type are you trying to extract?

[g-fb]

Wow, I forgot to link the sample project, here it is https://gitlab.com/g-fb/memory-extraction.

What OS are you in

openSUSE Tumbleweed

what archive type are you trying to extract?

There are 2 archive in the sample project, both trigger the issues.

[antony-jr]

@g-fb I don't think it's a bug with QArchive. It's a bug with the program itself. There are two types of allocation in C, C++ and pretty much every programming language (which allows you to do memory management). You allocated the QFile in Stack Memory here -> https://gitlab.com/g-fb/memory-extraction/-/blob/master/mainwindow.cpp#L53

QArchive is async so it will not block the method call. So when the QFile goes out of scope, it is destructed so the memory address becomes invalid.

Solution: Allocated the QFile in the heap with QFile *archive = new QFile(archivePath); and then delete it later when you are done using it.

I compiled your program with my modifications and it worked like a charm.

[g-fb]

Thanks for the explanation.

emits error even though the finished signal is emitted and the file names are printed by qDebug().

When I pass archiveFile directly sometimes it works sometimes it gives an error

Now I am getting the error even when I pass a QIODevice. It doesn't always happen, I have to open the archives a few times. ... Filename:: "astrology-astronomy-body-of-water-2406397.jpg" Filename:: "beautiful-flowers-flowers-white-flowers-2395252.jpg" QFileDevice::seek: IODevice is not open QFileDevice::seek: IODevice is not open An error has occured :: "QArchive::ArchiveCorrupted"

[antony-jr]

I can't reproduce this. In my computer it works fine. I will look into this more.

[antony-jr]

Also you can just simply pass the archive path as string to the constructor.

[antony-jr]

Can you please verify if this bug exists even if you do a fresh build in cmake.

[antony-jr]

I think I just reproduced your bug if I do the extraction continuously.... I think it's some kind of time based issue. I will look into this more.

[g-fb]

Also you can just simply pass the archive path as string to the constructor.

Same thing happens.

Can you please verify if this bug exists even if you do a fresh build in cmake.

The sample project pulls the master branch and builds it.

I think I just reproduced your bug if I do the extraction continuously.... I think it's some kind of time based issue. I will look into this more.

Thanks.

[antony-jr]

@g-fb does this issue happen all the time or only happens when you try to extract the same file very fastly. Ex: in my case this only occurs when I double click the same entry really fast, over and over again to get this error. Otherwise it seems to work without any issues. What is the case in your case?

[g-fb]

It doesn't happen everytime, but very often, even if I wait few seconds between extractions.

It even happens on the first extraction.

[g-fb]

The error seems to come from QCoreApplication::processEvents(); being inside the loop. If I move QCoreApplication::processEvents(); outside the loop I don't get the error anymore.

[antony-jr]

The error seems to come from QCoreApplication::processEvents(); being inside the loop. If I move QCoreApplication::processEvents(); outside the loop I don't get the error anymore.

That just means we need some delay and we are calling process events too fast.

[antony-jr]

Seems to be related with #46, the error is solved if we don't call getInfo() before start which is a bug. Will work on fixing it.

[antony-jr]

Should work now with the latest master.