panini 0.73 segfaults immediately on startup

[waltkelly]

It segfaults with both debug and release builds.

Commands to build:

$ make clean
$ make debug
$ ./panini /home/parz/Pictures/Images/Planets/Mars/PIA22908_fig1.jpg
$ ./panini /home/parz/Pictures/Images/Planets/Mars/PIA22908_fig1.jpg
qt5ct: using qt5ct plugin
Segmentation fault (core dumped)

ggdb backtrace:
segfault.txt

qmake generated Makefile (.txt extension added to be able to upload):
Makefile.txt

My system:

$ uname -a
Linux Manjusri 4.18.0-16-generic #17~18.04.1-Ubuntu SMP Tue Feb 12 13:35:51 UTC 2019 x86_64 x86_64 x86_64 GNU/Linux

[jubalh]

Can you also upload the picture?
Which Qt version are you using?
Which desktop environment are you using?
Whats the output of echo $QT_QPA_PLATFORMTHEME ?

Somehow it seems to be related to the Qt theme that is set.

[AdamMajer]

@waltkelly Do you see same crash if you do

./panini --platformtheme qgtk3 /home/parz/Pictures/Images/Planets/Mars/PIA22908_fig1.jpg

Since the segfault is in the setupUi(), which is autogenerated, it seems that there is a problem with your Qt install or the compiled application is not rebuilt properly. Remove all generated files and recompile would be first step.

[jubalh]

Getting the same now on my system:

#0  0x00007ffff79d46b0 in QWidget::hide() () from /usr/lib64/libQt5Widgets.so.5
#1  0x00007ffff7b3810d in ?? () from /usr/lib64/libQt5Widgets.so.5
#2  0x00007ffff7b39531 in QMenuBar::heightForWidth(int) const ()
   from /usr/lib64/libQt5Widgets.so.5
#3  0x00007ffff7b3c529 in QMenuBar::changeEvent(QEvent*) ()
   from /usr/lib64/libQt5Widgets.so.5
#4  0x00007ffff79eaf54 in QWidget::event(QEvent*) ()
   from /usr/lib64/libQt5Widgets.so.5
#5  0x00007ffff7b3c5eb in QMenuBar::event(QEvent*) ()
   from /usr/lib64/libQt5Widgets.so.5
#6  0x00007ffff79a8c62 in QApplicationPrivate::notify_helper(QObject*, QEvent*)
    () from /usr/lib64/libQt5Widgets.so.5
#7  0x00007ffff79b21e0 in QApplication::notify(QObject*, QEvent*) ()
   from /usr/lib64/libQt5Widgets.so.5
#8  0x00007ffff6f76562 in QCoreApplication::notifyInternal2(QObject*, QEvent*)
    () from /usr/lib64/libQt5Core.so.5
#9  0x00007ffff79dcb30 in QWidget::changeEvent(QEvent*) ()
   from /usr/lib64/libQt5Widgets.so.5
#10 0x00007ffff7b3c48a in QMenuBar::changeEvent(QEvent*) ()
   from /usr/lib64/libQt5Widgets.so.5
#11 0x00007ffff79eaf54 in QWidget::event(QEvent*) ()
   from /usr/lib64/libQt5Widgets.so.5
#12 0x00007ffff7b3c5eb in QMenuBar::event(QEvent*) ()

[jubalh]

@luis-pereira sorry for pinging you here. I know this is not LXQt ;) But I wanted to ask you if you see what's going on here?

[luis-pereira]

@jubalh Will take a quick look.

[luis-pereira]

@jubalh
Quick look
The crash is caused by the errMsgHandler() function. More specifically the QMessageBox::warning() or QMessage::critical() calls.

My guess is that your crash occurs when using qt5ct. Not qt5ct fault, tough. It's debug messages makes errMsgHandler() to be called and QMessage::warning() to be running triggering the crash.
To be certain, pls comment the QMessage::xxxxxxx in the errMsgHandler()and the crash should disappear.

[jubalh]

Thank you for checking @luis-pereira !

To be certain, pls comment the QMessage::xxxxxxx in the errMsgHandler()and the crash should disappear.

You are right. It compiles and runs fine without those.
But I don't see why this is happening. And why did it work earlier?

[luis-pereira]

It's probably a combination of bad timing and the exec() call that QMessageBox static methods use.
QErrorMessage does not work for you ?

[luis-pereira]

Were you using qt5ct before ?

[jubalh]

Were you using qt5ct before ?

I'm not sure. I never decided on using the one or the other consciously.
I'm not even sure where to set this. Probably this is just my Linux distro that set it for me?

[luis-pereira]

It's an environment variable.
echo ${QT_QPA_PLATFORMTHEME}

[jubalh]

Yes it's set to qt5ct:

echo ${QT_QPA_PLATFORMTHEME}
qt5ct

But I don't know what/where it was set. And what other values I should use. And I suppose I should change Panini so it works with whatever value is set there.

[luis-pereira]

But I don't know what/where it was set. And what other values I should use. And I suppose I should change Panini so it works with whatever value is set there.

Of course.
It's set by the start environment. In LXQt case, it's starlxqt. You can override it by exporting some other value to the QT_QPA_PLATFORMTHEME. Or for a single run with, for example: QT_QPA_PLATFORMTHEME=lxqt ./panini
I'm just trying to see if it's a Qt regression. I don't think so.

Why was QErrorMessage not used ?

[jubalh]

Why was QErrorMessage not used ?

I suppose there was no reason.

I could use:

-        QMessageBox::critical( 0, "pvQt", s );
+        errorMessageDialog = new QErrorMessage();
+        errorMessageDialog->showDialog(s);

But I think QErrorMessage(this) is needed and it's a static method, no?
Also I don't see a way to set criticial/warning right now.

[luis-pereira]

This should work:

diff --git a/src/MainWindow.cpp b/src/MainWindow.cpp
index f376161..c68cd5d 100755
--- a/src/MainWindow.cpp
+++ b/src/MainWindow.cpp
@@ -18,6 +18,7 @@
 */
 
 #include <QtGui>
+#include <QErrorMessage>
 #include <QSettings>
 #include <QMessageBox>
 #include "MainWindow.h"
@@ -32,20 +33,22 @@
 static void errMsgHandler( QtMsgType type, const QMessageLogContext &context, const QString &msg){
     QString s;
     bool die = false;
+    QErrorMessage *errorMessage = new QErrorMessage(nullptr);
+    errorMessage->setModal(true);
 
     switch( type ){
     case QtDebugMsg:
         s = "Debug: ";
     case QtWarningMsg:
         s += msg;
-        QMessageBox::warning( 0, "pvQt", s );
+        errorMessage->showMessage(s, "pvQt");
         break;
     case QtFatalMsg:
         die = true;
         s = "Fatal: ";
     case QtCriticalMsg:
         s += msg;
-        QMessageBox::critical( 0, "pvQt", s );
+        errorMessage->showMessage(s, "pvQt");
         break;
     }

[luis-pereira]

You can also use QMessageBox, but not the static methods.

[jubalh]

Thanks @luis-pereira !
I tried:

diff --git a/src/MainWindow.cpp b/src/MainWindow.cpp
index f376161..73666af 100755
--- a/src/MainWindow.cpp
+++ b/src/MainWindow.cpp
@@ -33,19 +33,21 @@ static void errMsgHandler( QtMsgType type, const QMessageLogContext &context, co
     QString s;
     bool die = false;
 
+    QMessageBox *err = new QMessageBox(nullptr);
+
     switch( type ){
     case QtDebugMsg:
         s = "Debug: ";
     case QtWarningMsg:
         s += msg;
-        QMessageBox::warning( 0, "pvQt", s );
+        err->warning( 0, "pvQt", s );
         break;
     case QtFatalMsg:
         die = true;
         s = "Fatal: ";
     case QtCriticalMsg:
         s += msg;
-        QMessageBox::critical( 0, "pvQt", s );
+        err->critical( 0, "pvQt", s );
         break;
     }

too. But this one segfaulted also.

But your solution works fine! :)