Display error message when unrecoverable error occurred

PR #19462.

src/app/application.cpp

@@ -759,7 +759,6 @@ void Application::processParams(const QBtCommandLineParameters &params)
 }
 
 int Application::exec()
-try
 {
 #if !defined(DISABLE_WEBUI) && defined(DISABLE_GUI)
     const QString loadingStr = tr("WebUI will be started shortly after internal preparations. Please wait...");
@@ -928,21 +927,6 @@ try
 
     return BaseApplication::exec();
 }
-catch (const RuntimeError &err)
-{
-#ifdef DISABLE_GUI
-    fprintf(stderr, "%s", qPrintable(err.message()));
-#else
-    QMessageBox msgBox;
-    msgBox.setIcon(QMessageBox::Critical);
-    msgBox.setText(QCoreApplication::translate("Application", "Application failed to start."));
-    msgBox.setInformativeText(err.message());
-    msgBox.show(); // Need to be shown or to moveToCenter does not work
-    msgBox.move(Utils::Gui::screenCenter(&msgBox));
-    msgBox.exec();
-#endif
-    return EXIT_FAILURE;
-}
 
 bool Application::isRunning()
 {

src/app/main.cpp

@@ -46,7 +46,7 @@
 #endif
 
 #include <QCoreApplication>
-#include <QDebug>
+#include <QString>
 #include <QThread>
 
 #ifndef DISABLE_GUI
@@ -86,6 +86,7 @@ using namespace std::chrono_literals;
 void displayVersion();
 bool userAgreesWithLegalNotice();
 void displayBadArgMessage(const QString &message);
+void displayErrorMessage(const QString &message);
 
 #ifndef DISABLE_GUI
 void showSplashScreen();
@@ -105,10 +106,12 @@ int main(int argc, char *argv[])
     // We must save it here because QApplication constructor may change it
     bool isOneArg = (argc == 2);
 
+    // `app` must be declared out of try block to allow display message box in case of exception
+    std::unique_ptr<Application> app;
     try
     {
         // Create Application
-        auto app = std::make_unique<Application>(argc, argv);
+        app = std::make_unique<Application>(argc, argv);
 
 #ifdef Q_OS_WIN
         // QCoreApplication::applicationDirPath() needs an Application object instantiated first
@@ -255,7 +258,7 @@ int main(int argc, char *argv[])
     }
     catch (const RuntimeError &er)
     {
-        qDebug() << er.message();
+        displayErrorMessage(er.message());
         return EXIT_FAILURE;
     }
 }
@@ -298,6 +301,30 @@ void displayBadArgMessage(const QString &message)
 #endif
 }
 
+void displayErrorMessage(const QString &message)
+{
+#ifndef DISABLE_GUI
+    if (QApplication::instance())
+    {
+        QMessageBox msgBox;
+        msgBox.setIcon(QMessageBox::Critical);
+        msgBox.setText(QCoreApplication::translate("Main", "An unrecoverable error occurred."));
+        msgBox.setInformativeText(message);
+        msgBox.show(); // Need to be shown or to moveToCenter does not work
+        msgBox.move(Utils::Gui::screenCenter(&msgBox));
+        msgBox.exec();
+    }
+    else
+    {
+        const QString errMsg = QCoreApplication::translate("Main", "qBittorrent has encountered an unrecoverable error.") + u'\n' + message + u'\n';
+        fprintf(stderr, "%s", qUtf8Printable(errMsg));
+    }
+#else
+    const QString errMsg = QCoreApplication::translate("Main", "qBittorrent has encountered an unrecoverable error.") + u'\n' + message + u'\n';
+    fprintf(stderr, "%s", qUtf8Printable(errMsg));
+#endif
+}
+
 bool userAgreesWithLegalNotice()
 {
     Preferences *const pref = Preferences::instance();

src/base/bittorrent/sessionimpl.cpp

@@ -3103,8 +3103,16 @@ void SessionImpl::generateResumeData()
 void SessionImpl::saveResumeData()
 {
     for (const TorrentImpl *torrent : asConst(m_torrents))
+    {
+        // When the session is terminated due to unrecoverable error
+        // some of the torrent handles can be corrupted
+        try
+        {
             torrent->nativeHandle().save_resume_data(lt::torrent_handle::only_if_modified);
-    m_numResumeData += m_torrents.size();
+            ++m_numResumeData;
+        }
+        catch (const std::exception &) {}
+    }
 
     // clear queued storage move jobs except the current ongoing one
     if (m_moveStorageQueue.size() > 1)

src/base/bittorrent/torrentimpl.cpp

@@ -50,6 +50,7 @@
 #include <QStringList>
 #include <QUrl>
 
+#include "base/exceptions.h"
 #include "base/global.h"
 #include "base/logger.h"
 #include "base/preferences.h"
@@ -1696,6 +1697,7 @@ void TorrentImpl::endReceivedMetadataHandling(const Path &savePath, const PathLi
 }
 
 void TorrentImpl::reload()
+try
 {
     m_completedFiles.fill(false);
     m_filesProgress.fill(0);
@@ -1738,6 +1740,11 @@ void TorrentImpl::reload()
 
     updateState();
 }
+catch (const lt::system_error &err)
+{
+    throw RuntimeError(tr("Failed to reload torrent. Torrent: %1. Reason: %2")
+            .arg(id().toString(), QString::fromLocal8Bit(err.what())));
+}
 
 void TorrentImpl::pause()
 {