Shutter SEGFAULTs on Ubuntu Touch on the Pine Phone Pro

[SumwunDucainest]

When starting shutter on Ubuntu Touch on the Pine Phone Pro, the app immediately shuts down.

Upon further inspection, that is because of a SEGFAULT.

We should investigate and fix.

[SumwunDucainest]

Using Clickable debugging, I was able to find the root cause:

Thread 1 received signal SIGSEGV, Segmentation fault.
std::__uniq_ptr_impl<libcamera::Extensible::Private, std::default_delete<libcamera::Extensible::Private> >::_M_ptr (this=0x60) at /usr/aarch64-linux-gnu/include/c++/9/bits/unique_ptr.h:154
warning: 154    /usr/aarch64-linux-gnu/include/c++/9/bits/unique_ptr.h: No such file or directory
(gdb)

(gdb) bt
#0  std::__uniq_ptr_impl<libcamera::Extensible::Private, std::default_delete<libcamera::Extensible::Private> >::_M_ptr (this=0x60) at /usr/aarch64-linux-gnu/include/c++/9/bits/unique_ptr.h:154
#1  0x0000fffff7c79b3c in std::unique_ptr<libcamera::Extensible::Private, std::default_delete<libcamera::Extensible::Private> >::get (this=0x60) at /usr/aarch64-linux-gnu/include/c++/9/bits/unique_ptr.h:361
#2  0x0000fffff7c775c0 in libcamera::Extensible::_d<libcamera::Camera::Private> (this=0x60) at ../include/libcamera/base/class.h:102
#3  0x0000fffff7c754a0 in libcamera::Camera::_d<true> (this=0x0) at ../include/libcamera/camera.h:116
#4  0x0000fffff7c72190 in libcamera::Camera::generateConfiguration (this=0x0, roles=...) at ../src/libcamera/camera.cpp:1092
#5  0x0000aaaaaaabd624 in CameraProxy::buildConfiguration(std::initializer_list<libcamera::StreamRole>) ()
#6  0x0000aaaaaaac1590 in CameraProxy::startViewFinder() ()
#7  0x0000aaaaaaaf76c0 in CameraProxy::qt_static_metacall(QObject*, QMetaObject::Call, int, void**) ()
#8  0x0000aaaaaaaf7a44 in CameraProxy::qt_metacall(QMetaObject::Call, int, void**) ()
#9  0x0000fffff5ed0ba0 in ?? () from target:/lib/aarch64-linux-gnu/libQt5Qml.so.5
#10 0x0000fffff5dbe784 in ?? () from target:/lib/aarch64-linux-gnu/libQt5Qml.so.5
#11 0x0000fffff5dc03d8 in ?? () from target:/lib/aarch64-linux-gnu/libQt5Qml.so.5
#12 0x0000fffff5dc1028 in QV4::QObjectMethod::callInternal(QV4::Value const*, QV4::Value const*, int) const () from target:/lib/aarch64-linux-gnu/libQt5Qml.so.5
#13 0x0000fffff5ddd5b8 in ?? () from target:/lib/aarch64-linux-gnu/libQt5Qml.so.5
#14 0x0000fffff5ddf3c0 in ?? () from target:/lib/aarch64-linux-gnu/libQt5Qml.so.5
#15 0x0000fffff5d7257c in QV4::Function::call(QV4::Value const*, QV4::Value const*, int, QV4::ExecutionContext const*) () from target:/lib/aarch64-linux-gnu/libQt5Qml.so.5
#16 0x0000fffff5ef81e0 in QQmlJavaScriptExpression::evaluate(QV4::CallData*, bool*) () from target:/lib/aarch64-linux-gnu/libQt5Qml.so.5
#17 0x0000fffff5e97398 in QQmlBoundSignalExpression::evaluate(void**) () from target:/lib/aarch64-linux-gnu/libQt5Qml.so.5
#18 0x0000fffff5e98568 in ?? () from target:/lib/aarch64-linux-gnu/libQt5Qml.so.5
#19 0x0000fffff5edc42c in QQmlNotifier::emitNotify(QQmlNotifierEndpoint*, void**) () from target:/lib/aarch64-linux-gnu/libQt5Qml.so.5
#20 0x0000fffff5e77284 in QQmlData::signalEmitted(QAbstractDeclarativeData*, QObject*, int, void**) () from target:/lib/aarch64-linux-gnu/libQt5Qml.so.5
#21 0x0000fffff589a2f4 in QMetaObject::activate(QObject*, int, int, void**) () from target:/lib/aarch64-linux-gnu/libQt5Core.so.5
#22 0x0000fffff5f88fe0 in QQmlTimer::event(QEvent*) () from target:/lib/aarch64-linux-gnu/libQt5Qml.so.5
#23 0x0000fffff586c98c in QCoreApplication::notifyInternal2(QObject*, QEvent*) () from target:/lib/aarch64-linux-gnu/libQt5Core.so.5
#24 0x0000fffff586f8a0 in QCoreApplicationPrivate::sendPostedEvents(QObject*, int, QThreadData*) () from target:/lib/aarch64-linux-gnu/libQt5Core.so.5
#25 0x0000fffff58c9990 in ?? () from target:/lib/aarch64-linux-gnu/libQt5Core.so.5
#26 0x0000fffff3ea594c in g_main_context_dispatch () from target:/lib/aarch64-linux-gnu/libglib-2.0.so.0
#27 0x0000fffff3ea5bbc in ?? () from target:/lib/aarch64-linux-gnu/libglib-2.0.so.0
#28 0x0000fffff3ea5c5c in g_main_context_iteration () from target:/lib/aarch64-linux-gnu/libglib-2.0.so.0
#29 0x0000fffff58c8e3c in QEventDispatcherGlib::processEvents(QFlags<QEventLoop::ProcessEventsFlag>) () from target:/lib/aarch64-linux-gnu/libQt5Core.so.5
#30 0x0000fffff586b138 in QEventLoop::exec(QFlags<QEventLoop::ProcessEventsFlag>) () from target:/lib/aarch64-linux-gnu/libQt5Core.so.5
#31 0x0000fffff587373c in QCoreApplication::exec() () from target:/lib/aarch64-linux-gnu/libQt5Core.so.5

What is happening, is that the m_currentCamera shared_ptr here is a nullptr, which leads to the SEGFAULT.