OpenLP will not start with QT4.8 with Impress enabled

[Wesley Stout]

On Fedora 16 (GNOME) fresh install (from repos) when I attempt to open OpenLP for the first time. I make it to the language selection then Fedora gives me this: Process /usr/bin/python was killed by signal 6 (SIGABRT). That didn't really help me much so I ran in debug mode and have attached openlp.log also.

[Raoul Snyman (raoul-snyman)]

This is an issue in PyQt4 in Fedora, see https://bugzilla.redhat.com/show_bug.cgi?id=752101. There is nothing we can do but wait.

[Wesley Stout (wesleystout)]

Here is a work around: Delete ~/.config/OpenLP/OpenLP.conf Then when the first run wizard runs again disable Presentations. OpenLP then works. I know that loses all of the users config settings but at least it works. I am sure there is a way to edit the config file to not fire up the presentation plugin also.

[Jonathan Corwin (j-corwin)]

If the bug isn't fixed soon, is it worth considering disabling the presentations setting in the Fedora 16 package?

[Wesley Stout (wesleystout)]

For anyone that stumbles upon this, I found this to work, and much cleaner than deleting your config file. Open ~/.config/OpenLP/OpenLP.conf and you will have this:

[Presentation]
status=1

change it to

status=0

This will disable the plugin without having to delete your config.

[Joe Mulloy (jdmulloy)]

This crash also occurs on openSUSE Factory (12.2), so it would appear to be a bug in QT4 and/or py-qt4. It's likely to start hitting other distros as well.

I've managed to create a small python program that exhibits this crash. I've found that it doesn't matter what program is executed. My program uses xterm, but any program should cause a crash. This program segfaults on Fedora 16 and openSUSE Factory. It exits cleanly on openSUSE 12.1 which has older versions of QT4 and py-qt4.

[Joe Mulloy (jdmulloy)]

It's not python-qt4, it's QT4 itself. I've attached the code that proves it. It's pretty much a C++ version of the python program I posted earlier. It runs fine in openSUSE 12.1 and crashes in openSUSE 12.2 in the exact same way the python example and OpenLP crash.

To build it you'll need your distro's C++ and QT4 development packages.

Follow these steps to build

mkdir qprocess_c++_test
cd qprocess_c++_test
<Put the file in this directory>
qmake -project
qmake qprocess_c++_test.pro
make

[Joe Mulloy (jdmulloy)]

Filled bug against openSUSE 12.2 Factory which also has this bug.

https://bugzilla.novell.com/show_bug.cgi?id=748241

[Tim Bentley (trb143)]

Kevin Kofler <email address hidden> changed:

          What |Removed |Added
----------------------------------------------------------------------------
         Component|qt |OpenLP
        AssignedTo|<email address hidden> |<email address hidden>

--- Comment #14 from Kevin Kofler <email address hidden> 2012-02-24 14:37:55 EST ---
You cannot waitForStarted() on a process started with startDetached().

startDetached is a static method of QProcess, which starts a process in a
fire&forget way, it does not track any state inside a QProcess object (in fact,
it can be run without any). Thus, you're running waitForStarted on a
default-constructed process where nothing is actually being started in the
first place.

[Joe Mulloy (jdmulloy)]

According to the RedHat bug report the problem is that OpenLP shouldn't be calling waitForStarted on this object. This should probably raise an exception instead of causing a buffer overflow, but the OpenLP code should still be corrected. Perhaps we should be using start instead of startDetached?