[fix] Segfault when editing pose in moveit_setup_assistant

[tylerjw]

Description

When the item() method is called it can return a nullptr if the row/column doesn't exist. Here is the documentation. The way to reproduce this before was to create a pose, then click edit on that pose, and then click Save. This would result in the stack trace below. The basics of it are that row is set to -1 by clearContents and that causes the callback previewClicked to be called because the row value changed. -1 is not a valid row index so item() returns nullptr and then we dereference it.

My fix just checks for nullptr before dereferencing and performing the rest of the logic in previewClicked. I tested this manually and was not able to reproduce the segfault.

Thread 1 "moveit_setup_as" received signal SIGSEGV, Segmentation fault.
moveit_setup_assistant::RobotPosesWidget::previewClicked (this=0x5555556be2f0, row=-1)
    at /home/tyler/workspace/ws_moveit_noetic/src/moveit/moveit_setup_assistant/src/widgets/robot_poses_widget.cpp:324
324	  const std::string& name = data_table_->item(row, 0)->text().toStdString();


(gdb) info stack
#0  moveit_setup_assistant::RobotPosesWidget::previewClicked(int, int, int, int) (this=0x5555556be2f0, row=-1)
    at /home/tyler/workspace/ws_moveit_noetic/src/moveit/moveit_setup_assistant/src/widgets/robot_poses_widget.cpp:324
#1  0x00007ffff7f04fae in moveit_setup_assistant::RobotPosesWidget::qt_static_metacall(QObject*, QMetaObject::Call, int, void**)
    (_o=<optimized out>, _c=<optimized out>, _id=<optimized out>, _a=<optimized out>)
    at /home/tyler/workspace/ws_moveit_noetic/build/moveit_setup_assistant/moveit_setup_assistant_widgets_autogen/RZ4CM6YYJ6/moc_robot_poses_widget.cpp:115
#2  0x00007ffff72ea300 in QMetaObject::activate(QObject*, int, int, void**) () at /lib/x86_64-linux-gnu/libQt5Core.so.5
#3  0x00007ffff7bf506d in QTableWidget::currentCellChanged(int, int, int, int) () at /lib/x86_64-linux-gnu/libQt5Widgets.so.5
#4  0x00007ffff72ea300 in QMetaObject::activate(QObject*, int, int, void**) () at /lib/x86_64-linux-gnu/libQt5Core.so.5
#5  0x00007ffff727a017 in QItemSelectionModel::currentChanged(QModelIndex const&, QModelIndex const&) ()
    at /lib/x86_64-linux-gnu/libQt5Core.so.5
#6  0x00007ffff727a1bc in QItemSelectionModel::clearCurrentIndex() () at /lib/x86_64-linux-gnu/libQt5Core.so.5
#7  0x00007ffff7bf6d07 in QTableWidget::clearContents() () at /lib/x86_64-linux-gnu/libQt5Widgets.so.5
#8  0x00007ffff7f42647 in moveit_setup_assistant::RobotPosesWidget::loadDataTable() (this=0x5555556be2f0)
    at /home/tyler/workspace/ws_moveit_noetic/src/moveit/moveit_setup_assistant/src/widgets/robot_poses_widget.cpp:737
#9  0x00007ffff7f47f3d in moveit_setup_assistant::RobotPosesWidget::doneEditing() (this=0x5555556be2f0)
    at /home/tyler/workspace/ws_moveit_noetic/src/moveit/moveit_setup_assistant/src/widgets/robot_poses_widget.cpp:708
#10 0x00007ffff7f04fae in moveit_setup_assistant::RobotPosesWidget::qt_static_metacall(QObject*, QMetaObject::Call, int, void**)
    (_o=<optimized out>, _c=<optimized out>, _id=<optimized out>, _a=<optimized out>)
    at /home/tyler/workspace/ws_moveit_noetic/build/moveit_setup_assistant/moveit_setup_assistant_widgets_autogen/RZ4CM6YYJ6/moc_robot_poses_widget.cpp:115
#11 0x00007ffff72ea300 in QMetaObject::activate(QObject*, int, int, void**) () at /lib/x86_64-linux-gnu/libQt5Core.so.5
#12 0x00007ffff7a20806 in QAbstractButton::clicked(bool) () at /lib/x86_64-linux-gnu/libQt5Widgets.so.5
#13 0x00007ffff7a20a2e in  () at /lib/x86_64-linux-gnu/libQt5Widgets.so.5
#14 0x00007ffff7a21e73 in  () at /lib/x86_64-linux-gnu/libQt5Widgets.so.5
#15 0x00007ffff7a22035 in QAbstractButton::mouseReleaseEvent(QMouseEvent*) () at /lib/x86_64-linux-gnu/libQt5Widgets.so.5
#16 0x00007ffff796e2b6 in QWidget::event(QEvent*) () at /lib/x86_64-linux-gnu/libQt5Widgets.so.5
#17 0x00007ffff792ba66 in QApplicationPrivate::notify_helper(QObject*, QEvent*) () at /lib/x86_64-linux-gnu/libQt5Widgets.so.5
#18 0x00007ffff7935343 in QApplication::notify(QObject*, QEvent*) () at /lib/x86_64-linux-gnu/libQt5Widgets.so.5
#19 0x00007ffff72be93a in QCoreApplication::notifyInternal2(QObject*, QEvent*) () at /lib/x86_64-linux-gnu/libQt5Core.so.5
#20 0x00007ffff7934457 in QApplicationPrivate::sendMouseEvent(QWidget*, QMouseEvent*, QWidget*, QWidget*, QWidget**, QPointer<QWidget>&, bool, bool) () at /lib/x86_64-linux-gnu/libQt5Widgets.so.5
#21 0x00007ffff798a35d in  () at /lib/x86_64-linux-gnu/libQt5Widgets.so.5
#22 0x00007ffff798d1ec in  () at /lib/x86_64-linux-gnu/libQt5Widgets.so.5
#23 0x00007ffff792ba66 in QApplicationPrivate::notify_helper(QObject*, QEvent*) () at /lib/x86_64-linux-gnu/libQt5Widgets.so.5
#24 0x00007ffff79350f0 in QApplication::notify(QObject*, QEvent*) () at /lib/x86_64-linux-gnu/libQt5Widgets.so.5
#25 0x00007ffff72be93a in QCoreApplication::notifyInternal2(QObject*, QEvent*) () at /lib/x86_64-linux-gnu/libQt5Core.so.5
#26 0x00007ffff60b97d3 in QGuiApplicationPrivate::processMouseEvent(QWindowSystemInterfacePrivate::MouseEvent*) ()
    at /lib/x86_64-linux-gnu/libQt5Gui.so.5
#27 0x00007ffff60bb10b in QGuiApplicationPrivate::processWindowSystemEvent(QWindowSystemInterfacePrivate::WindowSystemEvent*) ()
    at /lib/x86_64-linux-gnu/libQt5Gui.so.5
#28 0x00007ffff609535b in QWindowSystemInterface::sendWindowSystemEvents(QFlags<QEventLoop::ProcessEventsFlag>) ()
    at /lib/x86_64-linux-gnu/libQt5Gui.so.5
#29 0x00007fffec1f732e in  () at /lib/x86_64-linux-gnu/libQt5XcbQpa.so.5
#30 0x00007ffff575cfbd in g_main_context_dispatch () at /lib/x86_64-linux-gnu/libglib-2.0.so.0
#31 0x00007ffff575d240 in  () at /lib/x86_64-linux-gnu/libglib-2.0.so.0
#32 0x00007ffff575d2e3 in g_main_context_iteration () at /lib/x86_64-linux-gnu/libglib-2.0.so.0
#33 0x00007ffff7316565 in QEventDispatcherGlib::processEvents(QFlags<QEventLoop::ProcessEventsFlag>) ()
    at /lib/x86_64-linux-gnu/libQt5Core.so.5
#34 0x00007ffff72bd4db in QEventLoop::exec(QFlags<QEventLoop::ProcessEventsFlag>) () at /lib/x86_64-linux-gnu/libQt5Core.so.5
#35 0x00007ffff72c5246 in QCoreApplication::exec() () at /lib/x86_64-linux-gnu/libQt5Core.so.5
#36 0x000055555555e154 in main(int, char**) (argc=<optimized out>, argv=0x7fffffffce58)
    at /home/tyler/workspace/ws_moveit_noetic/src/moveit/moveit_setup_assistant/src/setup_assistant_main.cpp:107

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[felixvd]

I've noticed this issue before but didn't take the time to look into it. This solves it. Thanks for the fix.

[v4hn]

@felixvd According to my current knowledge you could have (squash)merged the patch after your review.

I will leave this open for you to merge 😸

Thank you for the patch @tylerjw ! I might have been affected by this a few weeks ago as well...

[felixvd]

You're right!