[Digikam-devel] [Bug 285849] digikam crashes when resizing the crop area

[Rudolf Leitgeb]

https://bugs.kde.org/show_bug.cgi?id=285849





--- Comment #6 from Rudolf Leitgeb <Rudolf Leitgeb gmx at>  2011-11-21 07:57:19 ---
Since the bug reported by me seems to be a NULL pointer dereference, valgrind
may not be the tool of choice. Looking at the offending code in
core/libs/dimg/filters/levels/histogramwidget.cpp you see some risky logic
before finally  a pointer is dereferenced.

I replaced the original code:

                         currentHistogram()->calculateInThread();

with the snippet:


   ImageHistogram* Histogram = currentHistogram();
        if (Histogram == NULL) {
                qDebug("Triggered histogram crash!");
                qDebug("Dumping class state:");

                // Current selection information.
                HistogramPainter* histogramPainter;

                qDebug("sixteenBits: %1d", d->sixteenBits);
                qDebug("guideVisible: %1d", d->guideVisible);
                qDebug("statisticsVisible: %1d", d->statisticsVisible);
                qDebug("inSelected: %1d", d->inSelected);
                qDebug("selectMode: %1d", d->selectMode);
                qDebug("showProgress: %1d", d->showProgress);
                qDebug("renderingType: %d", d->renderingType);
                qDebug("range: %d", d->range);
                qDebug("state: %d", (int)(d->state));
                qDebug("channelType: %d", (int)(d->channelType));
                qDebug("scaleType: %d", (int)(d->scaleType));
                qDebug("imageHistogram: %p", d->imageHistogram);
                qDebug("selectionHistogram: %p", d->selectionHistogram);
                qDebug("xmin: %f", d->xmin);
                qDebug("xminOrg: %f", d->xminOrg);
                qDebug("xmax: %f", d->xmax);
                qDebug("animationState: %d", d->animationState);
                qDebug("animation: %p", d->animation);
                qDebug("histogramPainter: %p", d->histogramPainter);
                qDebug("arguments:");
                qDebug("i_idata: %p, i_w: %ud, i_h: %ud", i_data, i_w, i_h);
                qDebug("i_sixteenBits: %1d", i_sixteenBits);
                qDebug("s_idata: %p, s_w: %ud, s_h: %ud", s_data, s_w, s_h);
                qDebug("showProgress: %1d", showProgress);
        } else {
                currentHistogram()->calculateInThread();
        }


If the bug triggers, I'll (should) get a full dump of the status of the object.
In a short editing session it has not triggered yet but I expect that to happen
sooner or later. Please let me know in advance if you would like to see other
variables or states in this dump, too.

Cheers,

Rudi

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