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Fix exception handling in Qt signal/slot system #376

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1da7836
Fix exception handling in Qt signal/slot system
metsma Sep 3, 2025
4d03c2c
Merge branch 'main' into exception
metsma Dec 8, 2025
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4 changes: 2 additions & 2 deletions src/controller/commands.hpp
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Original file line number Diff line number Diff line change
Expand Up @@ -40,8 +40,8 @@ class CommandType
NONE = -1
};

CommandType() = default;
constexpr CommandType(const CommandTypeEnum _value) : value(_value) {}
CommandType() noexcept = default;
constexpr CommandType(const CommandTypeEnum _value) noexcept : value(_value) {}

constexpr bool operator==(CommandTypeEnum other) const { return value == other; }
constexpr bool operator!=(CommandTypeEnum other) const { return value != other; }
Expand Down
235 changes: 109 additions & 126 deletions src/controller/controller.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -42,7 +42,7 @@ namespace
const QString RESP_TECH_ERROR = QStringLiteral("ERR_WEBEID_NATIVE_FATAL");
const QString RESP_USER_CANCEL = QStringLiteral("ERR_WEBEID_USER_CANCELLED");

QVariantMap makeErrorObject(const QString& errorCode, const QString& errorMessage)
QVariantMap makeErrorObject(const QString& errorCode, const QString& errorMessage) noexcept
{
return {{QStringLiteral("error"),
QVariantMap {
Expand All @@ -53,8 +53,8 @@ QVariantMap makeErrorObject(const QString& errorCode, const QString& errorMessag

} // namespace

void Controller::run()
{
void Controller::run() noexcept
try {
// If a command is passed, the application is in command-line mode, else in stdin/stdout mode.
const bool isInCommandLineMode = bool(command);
isInStdinMode = !isInCommandLineMode;
Expand All @@ -63,41 +63,38 @@ void Controller::run()
<< QCoreApplication::applicationVersion() << "running in"
<< (isInStdinMode ? "stdin/stdout" : "command-line") << "mode";

try {
// TODO: cut out stdin mode separate class to avoid bugs in safari mode
if (isInStdinMode) {
// In stdin/stdout mode we first output the version as required by the WebExtension
// and then wait for the actual command.
writeResponseToStdOut(
isInStdinMode,
{{QStringLiteral("version"), QCoreApplication::applicationVersion()}},
"get-version");

command = readCommandFromStdin();
}

REQUIRE_NON_NULL(command)
switch (command->first) {
case CommandType::ABOUT:
WebEidUI::showAboutPage();
return;
case CommandType::QUIT:
// If quit is requested, respond with empty JSON object and quit immediately.
qInfo() << "Quit requested, exiting";
writeResponseToStdOut(true, {}, "quit");
emit quit();
return;
default:
break;
}

commandHandler = getCommandHandler(*command);

startCommandExecution();

} catch (const std::exception& error) {
onCriticalFailure(error.what());
// TODO: cut out stdin mode separate class to avoid bugs in safari mode
if (isInStdinMode) {
// In stdin/stdout mode we first output the version as required by the WebExtension
// and then wait for the actual command.
writeResponseToStdOut(isInStdinMode,
{{QStringLiteral("version"), QCoreApplication::applicationVersion()}},
"get-version");

command = readCommandFromStdin();
}

REQUIRE_NON_NULL(command)
switch (command->first) {
case CommandType::ABOUT:
WebEidUI::showAboutPage();
return;
case CommandType::QUIT:
// If quit is requested, respond with empty JSON object and quit immediately.
qInfo() << "Quit requested, exiting";
writeResponseToStdOut(true, {}, "quit");
emit quit();
return;
default:
break;
}

commandHandler = getCommandHandler(*command);

startCommandExecution();

} catch (const std::exception& error) {
onCriticalFailure(error.what());
}

void Controller::startCommandExecution()
Expand All @@ -121,7 +118,7 @@ void Controller::startCommandExecution()
waitForCardThread->start();
}

void Controller::createWindow()
void Controller::createWindow() noexcept
{
window = WebEidUI::createAndShowDialog(commandHandler->commandType());
connect(this, &Controller::statusUpdate, window, &WebEidUI::onSmartCardStatusUpdate);
Expand All @@ -135,53 +132,46 @@ void Controller::createWindow()
}

void Controller::onCardsAvailable(
const std::vector<electronic_id::ElectronicID::ptr>& availableEids)
{
try {
REQUIRE_NON_NULL(commandHandler)
REQUIRE_NON_NULL(window)
REQUIRE_NOT_EMPTY_CONTAINS_NON_NULL_PTRS(availableEids)
const std::vector<electronic_id::ElectronicID::ptr>& availableEids) noexcept
try {
REQUIRE_NON_NULL(commandHandler)
REQUIRE_NON_NULL(window)
REQUIRE_NOT_EMPTY_CONTAINS_NON_NULL_PTRS(availableEids)

for (const auto& card : availableEids) {
const auto protocol =
card->smartcard().protocol() == SmartCard::Protocol::T0 ? "T=0" : "T=1";
qInfo() << "Card" << card->name() << "in reader" << card->smartcard().readerName()
<< "using protocol" << protocol;
}
for (const auto& card : availableEids) {
const auto protocol =
card->smartcard().protocol() == SmartCard::Protocol::T0 ? "T=0" : "T=1";
qInfo() << "Card" << card->name() << "in reader" << card->smartcard().readerName()
<< "using protocol" << protocol;
}

window->showWaitingForCardPage(commandHandler->commandType());
window->showWaitingForCardPage(commandHandler->commandType());

commandHandler->connectSignals(window);
commandHandler->connectSignals(window);

runCommandHandler(availableEids);
runCommandHandler(availableEids);

} catch (const std::exception& error) {
onCriticalFailure(error.what());
}
} catch (const std::exception& error) {
onCriticalFailure(error.what());
}

void Controller::runCommandHandler(const std::vector<ElectronicID::ptr>& availableEids)
{
try {
auto* commandHandlerRunThread =
new CommandHandlerRunThread(this, *commandHandler, availableEids);
connectRetry(commandHandlerRunThread);

// When the command handler run thread retrieves certificates successfully, call
// onCertificatesLoaded() that starts card event monitoring while user enters the PIN.
connect(commandHandler.get(), &CommandHandler::singleCertificateReady, this,
&Controller::onCertificatesLoaded);
connect(commandHandler.get(), &CommandHandler::multipleCertificatesReady, this,
&Controller::onCertificatesLoaded);

commandHandlerRunThread->start();

} catch (const std::exception& error) {
onCriticalFailure(error.what());
}
auto* commandHandlerRunThread =
new CommandHandlerRunThread(this, *commandHandler, availableEids);
connectRetry(commandHandlerRunThread);

// When the command handler run thread retrieves certificates successfully, call
// onCertificatesLoaded() that starts card event monitoring while user enters the PIN.
connect(commandHandler.get(), &CommandHandler::singleCertificateReady, this,
&Controller::onCertificatesLoaded);
connect(commandHandler.get(), &CommandHandler::multipleCertificatesReady, this,
&Controller::onCertificatesLoaded);

commandHandlerRunThread->start();
}

void Controller::onCertificatesLoaded()
void Controller::onCertificatesLoaded() noexcept
{
auto* cardEventMonitorThread = new CardEventMonitorThread(this, commandType());
connect(this, &Controller::stopCardEventMonitorThread, cardEventMonitorThread,
Expand All @@ -192,7 +182,7 @@ void Controller::onCertificatesLoaded()
cardEventMonitorThread->start();
}

void Controller::disposeUI()
void Controller::disposeUI() noexcept
{
if (window) {
window->disconnect();
Expand All @@ -202,60 +192,49 @@ void Controller::disposeUI()
}
}

void Controller::onConfirmCommandHandler(const EidCertificateAndPinInfo& certAndPinInfo)
{
void Controller::onConfirmCommandHandler(const EidCertificateAndPinInfo& certAndPinInfo) noexcept
try {
emit stopCardEventMonitorThread();

try {
auto* commandHandlerConfirmThread =
new CommandHandlerConfirmThread(this, *commandHandler, window, certAndPinInfo);
connect(commandHandlerConfirmThread, &CommandHandlerConfirmThread::completed, this,
&Controller::onCommandHandlerConfirmCompleted);
connectRetry(commandHandlerConfirmThread);
auto* commandHandlerConfirmThread =
new CommandHandlerConfirmThread(this, *commandHandler, window, certAndPinInfo);
connect(commandHandlerConfirmThread, &CommandHandlerConfirmThread::completed, this,
&Controller::onCommandHandlerConfirmCompleted);
connectRetry(commandHandlerConfirmThread);

commandHandlerConfirmThread->start();
commandHandlerConfirmThread->start();

} catch (const std::exception& error) {
onCriticalFailure(error.what());
}
} catch (const std::exception& error) {
onCriticalFailure(error.what());
}

void Controller::onCommandHandlerConfirmCompleted(const QVariantMap& res)
{
REQUIRE_NON_NULL(window)

void Controller::onCommandHandlerConfirmCompleted(const QVariantMap& res) noexcept
try {
qDebug() << "Command completed";

// Schedule application exit when the UI dialog is destroyed.
connect(window, &WebEidUI::destroyed, this, &Controller::exit);
_result = res;
writeResponseToStdOut(isInStdinMode, res, commandHandler->commandType());

try {
_result = res;
writeResponseToStdOut(isInStdinMode, res, commandHandler->commandType());
} catch (const std::exception& error) {
qCritical() << "Command" << std::string(commandType())
<< "fatal error while writing response to stdout:" << error;
}

window->quit();
exit();
} catch (const std::exception& error) {
qCritical() << "Command" << std::string(commandType())
<< "fatal error while writing response to stdout:" << error;
}

void Controller::onRetry()
{
try {
// Dispose the UI, it will be re-created during next execution.
disposeUI();
// Command handler signals are still connected, disconnect them so that they can be
// reconnected during next execution.
commandHandler->disconnect();
// Before restarting, wait until child threads finish.
waitForChildThreads();

startCommandExecution();

} catch (const std::exception& error) {
onCriticalFailure(error.what());
}
void Controller::onRetry() noexcept
try {
// Dispose the UI, it will be re-created during next execution.
disposeUI();
// Command handler signals are still connected, disconnect them so that they can be
// reconnected during next execution.
commandHandler->disconnect();
// Before restarting, wait until child threads finish.
waitForChildThreads();

startCommandExecution();

} catch (const std::exception& error) {
onCriticalFailure(error.what());
}

void Controller::connectRetry(const ControllerChildThread* childThread)
Expand All @@ -267,7 +246,7 @@ void Controller::connectRetry(const ControllerChildThread* childThread)
connect(childThread, &ControllerChildThread::cancel, this, &Controller::onDialogCancel);
}

void Controller::onDialogOK(const EidCertificateAndPinInfo& certAndPinInfo)
void Controller::onDialogOK(const EidCertificateAndPinInfo& certAndPinInfo) noexcept
{
if (commandHandler) {
onConfirmCommandHandler(certAndPinInfo);
Expand All @@ -277,16 +256,18 @@ void Controller::onDialogOK(const EidCertificateAndPinInfo& certAndPinInfo)
}
}

void Controller::onDialogCancel()
{
void Controller::onDialogCancel() noexcept
try {
qDebug() << "User cancelled";
_result = makeErrorObject(RESP_USER_CANCEL, QStringLiteral("User cancelled"));
writeResponseToStdOut(isInStdinMode, _result, commandType());
exit();
} catch (const std::exception& e) {
onCriticalFailure(e.what());
}

void Controller::onCriticalFailure(const QString& error)
{
void Controller::onCriticalFailure(const QString& error) noexcept
try {
emit stopCardEventMonitorThread();
qCritical() << "Exiting due to command" << std::string(commandType())
<< "fatal error:" << error;
Expand All @@ -304,16 +285,18 @@ void Controller::onCriticalFailure(const QString& error)
writeResponseToStdOut(isInStdinMode, _result, commandType());
}
exit();
} catch (const std::exception& e) {
qCritical() << "Failed to write stdout" << e.what();
}

void Controller::exit()
void Controller::exit() noexcept
{
disposeUI();
waitForChildThreads();
emit quit();
}

void Controller::waitForChildThreads()
void Controller::waitForChildThreads() noexcept
{
for (auto* thread : findChildren<QThread*>()) {
qDebug() << "Interrupting thread" << uintptr_t(thread);
Expand All @@ -324,7 +307,7 @@ void Controller::waitForChildThreads()
}
}

CommandType Controller::commandType()
CommandType Controller::commandType() const noexcept
{
return commandHandler ? commandHandler->commandType() : CommandType(CommandType::INSERT_CARD);
}
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