Crash on changing velocity of a note outside the piano roll

[kamnxt]

LMMS segfaults after changing the velocity of a note that has been pushed above B8.

How to reproduce:

1. Create two notes, one higher than the other.
2. Select both notes.
3. Drag bottom note all the way up until the top note is above B8.
4. Change velocity of the top note.

Notes can't be dragged below C0, but they can be dragged above B8 (which causes the problem).

[zonkmachine]

Yup, crashes it does. It's also possible to crash it in step 3 above by just draging the bottom note as high as you can if the interval is a Major second or bigger.

[musikBear]

I can not reproduce on win32 (1.1.90)
Both in top and bottom, notes that are dragged beyond the resp. c0 & b8, will just 'line up' on one note, no matter the previous position. Changing either velocity or pan for the out-of-view notes causes not a crash. If i use ctrl+a, i can bring the out-of-view note back into piano-roll, and it plays resizes and moves correctly.

[zonkmachine]

Bug introduced in f33d1f4 🚜

f33d1f4972b08234d372130be2b6633bfdf85f8d is the first bad commit
commit f33d1f4972b08234d372130be2b6633bfdf85f8d
Author: Vesa <contact.diizy@nbl.fi>
Date:   Wed Jul 9 19:18:17 2014 +0300

    Instrument track, mixer...

@Fastigium I have a hunch this is a case for you. Crash, playhandles, mutex...

The crash you get from changing velocity/pan is only when you drag the handle, not when you use the mouse scroll wheel.

bt full

Program terminated with signal SIGSEGV, Segmentation fault.
#0  0x000000000048e1bb in InstrumentTrack::processInEvent (this=0x20b13c0, event=..., time=..., offset=0)
    at /home/zonkmachine/builds/lmms/lmms/src/tracks/InstrumentTrack.cpp:360
360                         m_notes[event.key()]->setPanning( event.panning() );
(gdb) bt
#0  0x000000000048e1bb in InstrumentTrack::processInEvent (this=0x20b13c0, event=..., time=..., offset=0)
    at /home/zonkmachine/builds/lmms/lmms/src/tracks/InstrumentTrack.cpp:360
#1  0x000000000049b062 in PianoRoll::testPlayNote (this=0x1cd7320, n=0x2579a80) at /home/zonkmachine/builds/lmms/lmms/src/gui/PianoRoll.cpp:1994
#2  0x000000000049cb74 in PianoRoll::mouseMoveEvent (this=0x1cd7320, _me=0x7ffe0bcacfa0) at /home/zonkmachine/builds/lmms/lmms/src/gui/PianoRoll.cpp:2375
#3  0x00000000004a5995 in PianoRoll::mousePressEvent (this=0x1cd7320, _me=0x7ffe0bcacfa0) at /home/zonkmachine/builds/lmms/lmms/src/gui/PianoRoll.cpp:1624
#4  0x00007f774ae2138b in QWidget::event(QEvent*) () from /usr/lib/x86_64-linux-gnu/libQtGui.so.4
#5  0x00007f774add1e2c in QApplicationPrivate::notify_helper(QObject*, QEvent*) () from /usr/lib/x86_64-linux-gnu/libQtGui.so.4
#6  0x00007f774add85dd in QApplication::notify(QObject*, QEvent*) () from /usr/lib/x86_64-linux-gnu/libQtGui.so.4
#7  0x00007f774a6554dd in QCoreApplication::notifyInternal(QObject*, QEvent*) () from /usr/lib/x86_64-linux-gnu/libQtCore.so.4
#8  0x00007f774add7d93 in QApplicationPrivate::sendMouseEvent(QWidget*, QMouseEvent*, QWidget*, QWidget*, QWidget**, QPointer<QWidget>&, bool) ()
   from /usr/lib/x86_64-linux-gnu/libQtGui.so.4
#9  0x00007f774ae4c9eb in ?? () from /usr/lib/x86_64-linux-gnu/libQtGui.so.4
#10 0x00007f774ae4c289 in QApplication::x11ProcessEvent(_XEvent*) () from /usr/lib/x86_64-linux-gnu/libQtGui.so.4
#11 0x00007f774ae73b32 in ?? () from /usr/lib/x86_64-linux-gnu/libQtGui.so.4
#12 0x00007f77476d0e04 in g_main_context_dispatch () from /lib/x86_64-linux-gnu/libglib-2.0.so.0
#13 0x00007f77476d1048 in ?? () from /lib/x86_64-linux-gnu/libglib-2.0.so.0
#14 0x00007f77476d10ec in g_main_context_iteration () from /lib/x86_64-linux-gnu/libglib-2.0.so.0
#15 0x00007f774a6827a1 in QEventDispatcherGlib::processEvents(QFlags<QEventLoop::ProcessEventsFlag>) () from /usr/lib/x86_64-linux-gnu/libQtCore.so.4
#16 0x00007f774ae73be6 in ?? () from /usr/lib/x86_64-linux-gnu/libQtGui.so.4
#17 0x00007f774a6540af in QEventLoop::processEvents(QFlags<QEventLoop::ProcessEventsFlag>) () from /usr/lib/x86_64-linux-gnu/libQtCore.so.4
#18 0x00007f774a6543a5 in QEventLoop::exec(QFlags<QEventLoop::ProcessEventsFlag>) () from /usr/lib/x86_64-linux-gnu/libQtCore.so.4
#19 0x00007f774a659b79 in QCoreApplication::exec() () from /usr/lib/x86_64-linux-gnu/libQtCore.so.4
#20 0x00000000004830b3 in main (argc=1, argv=<optimized out>) at /home/zonkmachine/builds/lmms/lmms/src/core/main.cpp:503

[Fastigium]

@zonkmachine Thanks for the 🚜!

But about this issue: isn't the real problem that it's possible at all to push notes beyond piano roll boundaries? If I were to fix that, this bug would be fixed, too, right?

[zonkmachine]

If I were to fix that, this bug would be fixed, too, right?

Probably...
I'm a bit curious about why you can scroll but not drag the pan/velocity handle.

[Fastigium]

@zonkmachine Scrolling takes a different code path, via PianoRoll::wheelEvent() instead of PianoRoll::mousePressEvent() 😉

[Teuthis]

I have submitted a pull request for this bug. This is my very first pull request (and my first time using Git), so I hope I observed proper procedure and etiquette.

[tresf]

I have submitted a pull request for this bug. This is my very first pull request (and my first time using Git), so I hope I observed proper procedure and etiquette.

Yes you did. One nice trick is to put the words Closes #2713 in the description (rather than the title), which links the merge and the close operations from a bug-tracking perspective.

Also, the title of the PR could be a bit more descriptive. Fix for issue #2713 is hard to understand when reviewing history. Prevent crash when changing note velocity would be a bit better.

This is all minor though. Thanks for the patch. Merging.

[tresf]

Closed via 946ae85