[Qt-interest] Bug in QNetworkReply abort

Tue Jul 27 16:28:06 CEST 2010

On Tue, Jul 27, 2010 at 6:35 PM, Stanislav Kolar <skolar at kerio.com> wrote:
> Thank you for all responses - the problem was in my code ;-) I called qApp->processEvents() in the downloadProgress slot, which isn't probably acceptable..

downloadProgress() isn't blocking, so you need not call
processEvents() since they would be processed by the event loop anyway
when the slot returns.

Though I'm not sure why removing processEvents() solved it for you
(some sort of event processing recurssion)! :)

Maybe somebody else on the list could shed some light on it.

Regards,
-mandeep

>
> Stanislav Kolar
> Research & Development
> .................................................................
> Kerio Technologies
> Anglicke nabrezi 1, 301 49 Plzen
> Czech Republic
> tel. 377 338 901, fax 377 338 921
> www.kerio.com
> .................................................................
> Connect. Communicate. Collaborate. Securely.
>
>
> -----Original Message-----
> From: Mandeep Sandhu [mailto:mandeepsandhu.chd at gmail.com]
> Sent: Thursday, July 22, 2010 6:39 AM
> To: Stanislav Kolar
> Cc: qt-interest at trolltech.com
> Subject: Re: [Qt-interest] Bug in QNetworkReply abort
>
> I've been using QNAM and co. for a while now. I've not experienced any
> bugs yet (though I've not used the  post method yet).
>
> Are you certain you have a valid QNetworkReply pointer when you are
> calling abort (maybe you have called delete/deleteLater() in the reply
> processing slot)?
>
> I had a similar problem where my reply pointer was not valid. I found
> the problem when I used QPointer<QNetworkReply> for storing the reply
> pointer and checking if it was null or not before accessing any fxn.
>
> Can you check if you have a valid pointer when calling abort.
>
> HTH,
> -mandeep
>
> On Wed, Jul 21, 2010 at 8:16 PM, Stanislav Kolar <skolar at kerio.com> wrote:
>> Hi all,
>>
>> there is probably a bug in QNetworkAccessManager.
>> If I call QNetworkReply::abort(), the application crashes. The reply object is result of QNetworkAccessManager::post method.
>>
>> The call stack is
>> ================================
>> QtCored4.dll!QScopedPointer<QObjectData,QScopedPointerDeleter<QObjectData> >::data()  Line 135 + 0x3 bytes      C++
>> QtCored4.dll!qGetPtrHelper<QScopedPointer<QObjectData,QScopedPointerDeleter<QObjectData> > >(const QScopedPointer<QObjectData,QScopedPointerDeleter<QObjectData> > & p={...})  Line 2314 + 0xb bytes    C++
>> QtCored4.dll!QObject::d_func()  Line 125 + 0x13 bytes   C++
>> QtCored4.dll!QMetaObject::activate(QObject * sender=0x00000000, const QMetaObject * m=0x6415efac, int local_signal_index=0x00000007, void * * argv=0x0012d530)  Line 3210 + 0xc bytes   C++
>> QtNetworkd4.dll!QHttpNetworkReply::dataSendProgress(__int64 _t1=0x0000000001014000, __int64 _t2=0x000000000134fac9)  Line 146 + 0x15 bytes      C++
>> QtNetworkd4.dll!QHttpNetworkConnectionChannel::sendRequest()  Line 268  C++
>> QtNetworkd4.dll!QHttpNetworkConnectionChannel::_q_bytesWritten(__int64 bytes=0x0000000000008000)  Line 877      C++
>> QtNetworkd4.dll!QHttpNetworkConnectionChannel::qt_metacall(QMetaObject::Call _c=InvokeMetaMethod, int _id=0x00000001, void * * _a=0x0012d7e4)  Line 91 + 0x15 bytes     C++
>> QtCored4.dll!QMetaObject::metacall(QObject * object=0x015554ac, QMetaObject::Call cl=InvokeMetaMethod, int idx=0x00000005, void * * argv=0x0012d7e4)  Line 238  C++
>> QtCored4.dll!QMetaObject::activate(QObject * sender=0x0151e310, const QMetaObject * m=0x67304f48, int local_signal_index=0x00000001, void * * argv=0x0012d7e4)  Line 3287 + 0x27 bytes  C++
>> QtCored4.dll!QIODevice::bytesWritten(__int64 _t1=0x0000000000008000)  Line 98 + 0x14 bytes      C++
>> QtNetworkd4.dll!QAbstractSocketPrivate::flush()  Line 771       C++
>> QtNetworkd4.dll!QAbstractSocketPrivate::canWriteNotification()  Line 685        C++
>> QtNetworkd4.dll!QAbstractSocketPrivate::writeNotification()  Line 78 + 0x15 bytes       C++
>> QtNetworkd4.dll!QAbstractSocketEngine::writeNotification()  Line 161    C++
>> QtNetworkd4.dll!QWriteNotifier::event(QEvent * e=0x0012dd78)  Line 1130 C++
>> QtGuid4.dll!QApplicationPrivate::notify_helper(QObject * receiver=0x015877c8, QEvent * e=0x0012dd78)  Line 4302 + 0x11 bytes    C++
>> QtGuid4.dll!QApplication::notify(QObject * receiver=0x015877c8, QEvent * e=0x0012dd78)  Line 3706 + 0x10 bytes  C++
>> QtCored4.dll!QCoreApplication::notifyInternal(QObject * receiver=0x015877c8, QEvent * event=0x0012dd78)  Line 726 + 0x15 bytes  C++
>> QtCored4.dll!QCoreApplication::sendEvent(QObject * receiver=0x015877c8, QEvent * event=0x0012dd78)  Line 215 + 0x39 bytes       C++
>> QtCored4.dll!qt_internal_proc(HWND__ * hwnd=0x004b028c, unsigned int message=0x00000400, unsigned int wp=0x0000015c, long lp=0x00000002)  Line 478 + 0xf bytes  C++
>> user32.dll!_InternalCallWinProc at 20()  + 0x28 bytes
>> user32.dll!_UserCallWinProcCheckWow at 32()  + 0xb7 bytes
>> user32.dll!_DispatchMessageWorker at 8()  + 0xdc bytes
>> user32.dll!_DispatchMessageW at 4()  + 0xf bytes
>> QtCored4.dll!QEventDispatcherWin32::processEvents(QFlags<enum QEventLoop::ProcessEventsFlag> flags={...})  Line 781     C++
>> QtGuid4.dll!QGuiEventDispatcherWin32::processEvents(QFlags<enum QEventLoop::ProcessEventsFlag> flags={...})  Line 1145 + 0x15 bytes     C++
>> QtCored4.dll!QEventLoop::processEvents(QFlags<enum QEventLoop::ProcessEventsFlag> flags={...})  Line 150        C++
>> QtCored4.dll!QEventLoop::exec(QFlags<enum QEventLoop::ProcessEventsFlag> flags={...})  Line 201 + 0x2d bytes    C++
>> QtCored4.dll!QCoreApplication::exec()  Line 1003 + 0x15 bytes   C++
>> QtGuid4.dll!QApplication::exec()  Line 3582     C++
>>
>> It seems that the loop in
>>
>> bool QHttpNetworkConnectionChannel::sendRequest()
>>
>> tries to
>>
>> emit reply->dataSendProgress(written, bytesTotal);
>>
>> even though QHttpNetworkReply *reply is already destroyed - it is deleted by destructor of QNetworkAccessHttpBacked - the QHttpNetworkReply object is its children:
>>
>> QtNetworkd4.dll!QHttpNetworkReply::~QHttpNetworkReply()  Line 64        C++
>> QtNetworkd4.dll!QHttpNetworkReply::`scalar deleting destructor'()  + 0xf bytes  C++
>> QtCored4.dll!QObjectPrivate::deleteChildren()  Line 1978 + 0x24 bytes   C++
>> QtCored4.dll!QObject::~QObject()  Line 977      C++
>> QtNetworkd4.dll!QNetworkAccessBackend::~QNetworkAccessBackend()  Line 157 + 0x9 bytes   C++
>> QtNetworkd4.dll!QNetworkAccessHttpBackend::~QNetworkAccessHttpBackend()  Line 309 + 0x3d bytes  C++
>> QtNetworkd4.dll!QNetworkAccessHttpBackend::`scalar deleting destructor'()  + 0xf bytes  C++
>> QtCored4.dll!qDeleteInEventHandler(QObject * o=0x01587a08)  Line 3993 + 0x21 bytes      C++
>> QtCored4.dll!QObject::event(QEvent * e=0x01ffa7b8)  Line 1223 + 0xc bytes       C++
>> QtGuid4.dll!QApplicationPrivate::notify_helper(QObject * receiver=0x01587a08, QEvent * e=0x01ffa7b8)  Line 4302 + 0x11 bytes    C++
>> QtGuid4.dll!QApplication::notify(QObject * receiver=0x01587a08, QEvent * e=0x01ffa7b8)  Line 3706 + 0x10 bytes  C++
>> QtCored4.dll!QCoreApplication::notifyInternal(QObject * receiver=0x01587a08, QEvent * event=0x01ffa7b8)  Line 726 + 0x15 bytes  C++
>> ..
>>
>>
>> Did I something wrong ? Is it a known bug ? Or have somebody some advise/question ?
>>
>> Stanislav Kolar
>> Research & Development
>> .................................................................
>> Kerio Technologies
>> Anglicke nabrezi 1, 301 49 Plzen
>> Czech Republic
>> tel. 377 338 901, fax 377 338 921
>> www.kerio.com
>> .................................................................
>> Connect. Communicate. Collaborate. Securely.
>>
>>
>>
>>
>> _______________________________________________
>> Qt-interest mailing list
>> Qt-interest at trolltech.com
>> http://lists.trolltech.com/mailman/listinfo/qt-interest
>>
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