Command-line render segfaults if ~/.lmmsrc.xml cannot be written

[Wallacoloo]

This seems like a pretty obscure bug, but it comes down to ConfigManager trying to show a QMessageBox when the gui doesn't exist. All you have to do is chown root ~/.lmmsrc.xml and then launch lmms -r path/to/file.mmpz and you'll segfault.

Backtrace:

#0  0x00007ffff42f0267 in __GI_raise (sig=sig@entry=6) at ../sysdeps/unix/sysv/linux/raise.c:55
#1  0x00007ffff42f1eca in __GI_abort () at abort.c:89
#2  0x00007ffff67faa8a in qt_message_output(QtMsgType, char const*) () from /usr/lib/x86_64-linux-gnu/libQtCore.so.4
#3  0x00007ffff67fadf9 in ?? () from /usr/lib/x86_64-linux-gnu/libQtCore.so.4
#4  0x00007ffff67fb6e1 in qFatal(char const*, ...) () from /usr/lib/x86_64-linux-gnu/libQtCore.so.4
#5  0x00007ffff70deb24 in QWidgetPrivate::init(QWidget*, QFlags<Qt::WindowType>) () from /usr/lib/x86_64-linux-gnu/libQtGui.so.4
#6  0x00007ffff70def94 in QWidget::QWidget(QWidgetPrivate&, QWidget*, QFlags<Qt::WindowType>) () from /usr/lib/x86_64-linux-gnu/libQtGui.so.4
#7  0x00007ffff7562532 in QDialog::QDialog(QDialogPrivate&, QWidget*, QFlags<Qt::WindowType>) () from /usr/lib/x86_64-linux-gnu/libQtGui.so.4
#8  0x00007ffff758374c in QMessageBox::QMessageBox(QMessageBox::Icon, QString const&, QString const&, QFlags<QMessageBox::StandardButton>, QWidget*, QFlags<Qt::WindowType>) () from /usr/lib/x86_64-linux-gnu/libQtGui.so.4
#9  0x00007ffff75839e6 in ?? () from /usr/lib/x86_64-linux-gnu/libQtGui.so.4
#10 0x00007ffff7583c6f in QMessageBox::critical(QWidget*, QString const&, QString const&, QFlags<QMessageBox::StandardButton>, QMessageBox::StandardButton) ()
   from /usr/lib/x86_64-linux-gnu/libQtGui.so.4
#11 0x00000000004e9fc5 in ConfigManager::saveConfigFile (this=0x7fffea1ce020) at /home/colin/src/lmms/src/core/ConfigManager.cpp:517
#12 0x00000000004e7935 in ConfigManager::addRecentlyOpenedProject (this=0x7fffea1ce020, _file=...) at /home/colin/src/lmms/src/core/ConfigManager.cpp:229
#13 0x00000000005476c8 in Song::loadProject (this=0x97c950, fileName=...) at /home/colin/src/lmms/src/core/Song.cpp:1049
#14 0x00000000004d5854 in main (argc=5, argv=0x7fffffffe0f8) at /home/colin/src/lmms/src/core/main.cpp:515

I'm going to assign this to myself & fix it in the coming days.

[Wallacoloo]

For what it's worth, rendering is still functional when using the gui, if ~/.lmmsrc.xml is unwritable.

[tresf]

@Wallacoloo,

We should probably disable config writing when there's no GUI.

However, I've tested your theory about the QMessageBox with the following change and I still receive a segfault so I believe we have a few segfaults related to command line rendering on master. 👍

QString err = MainWindow::tr( "Could not save configuration file %1. "
                    "You're probably not permitted to "
                    "write to this file.\n"
                    "Please make sure you have write-"
                    "access to the file and try again." ).
                            arg( m_lmmsRcFile  );
        if ( gui )
        {       
            QMessageBox::critical( NULL,
                MainWindow::tr( "Could not save config-file" ),
                err );
        }
        return;

[tresf]

Related: #588

[zonkmachine]

It's trying to write ./lmmsrc.xml twice. First when opening the project it's calling ConfigManager::addRecentlyOpenedProject() and on closing ConfigManager::~ConfigManager() calls saveConfigFile() again.

- Maybe not add projects rendered from the command line to recently opened projects. if( gui ) ...

• Check If( gui ) and maybe printf a line but don't exit. The render works now.