Re: Possible bug in documentation.cc (de-referencing nullpointer)

[Andreas Weber]

Am 02.01.19 um 23:02 schrieb Andreas Weber:
> I've just changed line 102 to
> if (! m_help_engine->setupData() || 1)
> then rebuilt, executed and got the expected segfault (which obviously is 
> at another place)

Here a backtrace after modifying line 102 (simulating that 
m_help_engine->setupData() fails):

Thread 1 "octave-gui" received signal SIGSEGV, Segmentation fault.
0x00007f92868b4f70 in QKeySequence::operator==(QKeySequence const&) 
const () from /usr/lib/x86_64-linux-gnu/libQt5Gui.so.5
(gdb) bt
#0  0x00007f92868b4f70 in QKeySequence::operator==(QKeySequence const&) 
const () from /usr/lib/x86_64-linux-gnu/libQt5Gui.so.5
#1  0x00007f9286e2b04e in QAction::setShortcut(QKeySequence const&) () 
from /usr/lib/x86_64-linux-gnu/libQt5Widgets.so.5
#2  0x00007f928b095218 in octave::shortcut_manager::do_set_shortcut 
(this=0x55c8433c26f0, action=0x55c8437151a0, key=...) at 
../octave-src/libgui/src/shortcut-manager.cc:515
#3  0x00007f928afdb9a7 in octave::shortcut_manager::set_shortcut 
(action=0x55c8437151a0, key=...) at 
../octave-src/libgui/src/shortcut-manager.h:96
#4  0x00007f928afd77d5 in octave::documentation::notice_settings 
(this=0x55c84373e230, settings=0x55c8433ca940) at 
../octave-src/libgui/src/documentation.cc:551
#5  0x00007f928afd363c in 
octave::documentation_dock_widget::notice_settings (this=0x55c84367bc80, 
settings=0x55c8433ca940)
    at ../octave-src/libgui/src/documentation-dock-widget.cc:62
#6  0x00007f928b048216 in octave::octave_dock_widget::handle_settings 
(this=0x55c84367bc80, settings=0x55c8433ca940) at 
../octave-src/libgui/src/octave-dock-widget.cc:461
#7  0x00007f928b0e127b in octave::octave_dock_widget::qt_static_metacall 
(_o=0x55c84367bc80, _c=QMetaObject::InvokeMetaMethod, _id=7, 
_a=0x7ffe2e875280)
    at libgui/src/moc-octave-dock-widget.cc:274
#8  0x00007f92865785e9 in QMetaObject::activate(QObject*, int, int, 
void**) () from /usr/lib/x86_64-linux-gnu/libQt5Core.so.5
#9  0x00007f928b0d7223 in octave::main_window::settings_changed 
(this=0x55c843340800, _t1=0x55c8433ca940) at 
libgui/src/moc-main-window.cc:948
#10 0x00007f928b02bb88 in octave::main_window::read_settings 
(this=0x55c843340800) at ../octave-src/libgui/src/main-window.cc:1274
#11 0x00007f928b02570a in octave::main_window::main_window 
(this=0x55c843340800, oct_qt_app=..., oct_qt_lnk=0x55c8431a7ce0) at 
../octave-src/libgui/src/main-window.cc:268
#12 0x00007f928b035bcb in octave::octave_qt_app::create_main_window 
(this=0x7ffe2e875620) at ../octave-src/libgui/src/main-window.cc:2911
#13 0x00007f928b03587b in octave::octave_qt_app::octave_qt_app 
(this=0x7ffe2e875620, app_context=...) at 
../octave-src/libgui/src/main-window.cc:2865
#14 0x00007f928b049dab in octave::gui_application::execute 
(this=0x7ffe2e8756c0) at ../octave-src/libgui/src/octave-gui.cc:62
#15 0x000055c842455877 in main (argc=9, argv=0x7ffe2e8759f8) at 
../octave-src/src/main-gui.cc:103