[Interest] QBuffer::seek warnings in QtConcurrent

[Giuseppe D'Angelo]

Il 27/01/2015 20:27, Igor Mironchik ha scritto:
> I've looked at qjpeghandler.cpp and it is strangely that practically all
> of my photos produced by my Android camera is corrupted. Do you know any
> software that can give me information about exif in jpeg that I can be
> sure that jpeg is corrupted? Thank you.

Possibly exiftool or some any other image manipulation program.

But also I wonder about the code around your backtrace:

> 0	qt_message_fatal	qlogging.cpp	1407	0x57ed3f21	
> 1	QMessageLogger::warning	qlogging.cpp	396	0x57ed28bb	
> 2	QBuffer::seek	qbuffer.cpp	374	0x5807b386	
> 3	QDataStream::skipRawData	qdatastream.cpp	1169	0x5807dfbc	
> 4	getExifOrientation	qjpeghandler.cpp	820	0x5ab66204	

=>

>     795     quint32 offset;
>     ...
>     811     stream >> offset;
>     812     // we have already used 8 bytes of TIFF header
>     813     offset -= 8;
>     814
>     815     // read IFD
>     816     while (!stream.atEnd()) {
>     817         quint16 numEntries;
>     818
>     819         // skip offset bytes to get the next IFD
>     820         if (stream.skipRawData(offset) != (qint32)offset)
>     821             return -1;

Note in particular that "stream" reads an unsigned 32 bit int into 
offset, but then skipRawData silently converts to signed... (but it may 
be totally unrelated with the problem here, which perhaps results from 
bad EXIF parsing on Qt side)

HTH,
-- 
Giuseppe D'Angelo | giuseppe.dangelo at kdab.com | Software Engineer
KDAB (UK) Ltd., a KDAB Group company
Tel. UK +44-1738-450410, Sweden (HQ) +46-563-540090
KDAB - Qt Experts - Platform-independent software solutions

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