Improve error message when daemonizing failed

PR #19959.

src/app/application.cpp

@@ -292,7 +292,8 @@ Application::Application(int &argc, char **argv)
     connect(this, &QGuiApplication::commitDataRequest, this, &Application::shutdownCleanup, Qt::DirectConnection);
 #endif
 
-    LogMsg(tr("qBittorrent %1 started", "qBittorrent v3.2.0alpha started").arg(QStringLiteral(QBT_VERSION)));
+    LogMsg(tr("qBittorrent %1 started. Process ID: %2", "qBittorrent v3.2.0alpha started")
+        .arg(QStringLiteral(QBT_VERSION), QString::number(QCoreApplication::applicationPid())));
     if (portableModeEnabled)
     {
         LogMsg(tr("Running in portable mode. Auto detected profile folder at: %1").arg(profileDir.toString()));
@@ -944,7 +945,7 @@ int Application::exec()
     return BaseApplication::exec();
 }
 
-bool Application::isRunning()
+bool Application::hasAnotherInstance() const
 {
     return !m_instanceManager->isFirstInstance();
 }

src/app/application.h

@@ -101,7 +101,7 @@ public:
 
     int exec();
 
-    bool isRunning();
+    bool hasAnotherInstance() const;
     bool callMainInstance();
     const QBtCommandLineParameters &commandLineArgs() const;
 

src/app/main.cpp

@@ -73,6 +73,7 @@ Q_IMPORT_PLUGIN(QICOPlugin)
 #endif // DISABLE_GUI
 
 #include "base/global.h"
+#include "base/logger.h"
 #include "base/preferences.h"
 #include "base/profile.h"
 #include "base/version.h"
@@ -125,7 +126,7 @@ int main(int argc, char *argv[])
 #ifdef Q_OS_WIN
         // QCoreApplication::applicationDirPath() needs an Application object instantiated first
         // Let's hope that there won't be a crash before this line
-        const char *envName = "_NT_SYMBOL_PATH";
+        const char envName[] = "_NT_SYMBOL_PATH";
         const QString envValue = qEnvironmentVariable(envName);
         if (envValue.isEmpty())
             qputenv(envName, Application::applicationDirPath().toLocal8Bit());
@@ -185,13 +186,13 @@ int main(int argc, char *argv[])
             setCurrentMigrationVersion();
         }
 
-        // Check if qBittorrent is already running for this user
+        // Check if qBittorrent is already running
-        if (app->isRunning())
+        if (app->hasAnotherInstance())
         {
 #if defined(DISABLE_GUI) && !defined(Q_OS_WIN)
             if (params.shouldDaemonize)
             {
-                throw CommandLineParameterError(QCoreApplication::translate("Main", "You cannot use %1: qBittorrent is already running for this user.")
+                throw CommandLineParameterError(QCoreApplication::translate("Main", "You cannot use %1: qBittorrent is already running.")
                                      .arg(u"-d (or --daemon)"_s));
             }
 #endif
@@ -221,8 +222,7 @@ int main(int argc, char *argv[])
         // Since Apple made difficult for users to set PATH, we set here for convenience.
         // Users are supposed to install Homebrew Python for search function.
         // For more info see issue #5571.
-        QByteArray path = "/usr/local/bin:";
+        const QByteArray path = "/usr/local/bin:" + qgetenv("PATH");
-        path += qgetenv("PATH");
         qputenv("PATH", path.constData());
 
         // On OS X the standard is to not show icons in the menus
@@ -235,19 +235,27 @@ int main(int argc, char *argv[])
 #if defined(DISABLE_GUI) && !defined(Q_OS_WIN)
         if (params.shouldDaemonize)
         {
-            app.reset(); // Destroy current application
+            app.reset(); // Destroy current application instance
-            if (daemon(1, 0) == 0)
+            if (::daemon(1, 0) == 0)
             {
                 app = std::make_unique<Application>(argc, argv);
-                if (app->isRunning())
+                if (app->hasAnotherInstance())
                 {
-                    // Another instance had time to start.
+                    // It is undefined behavior to write to log file since there is another qbt instance
+                    // in play. But we still do it since there is chance that the log message will survive.
+                    const QString errorMessage = QCoreApplication::translate("Main", "Found unexpected qBittorrent instance. Exiting this instance. Current process ID: %1.")
+                        .arg(QString::number(QCoreApplication::applicationPid()));
+                    LogMsg(errorMessage, Log::CRITICAL);
+                    // stdout, stderr is closed so we can't use them
                     return EXIT_FAILURE;
                 }
             }
             else
             {
-                qCritical("Something went wrong while daemonizing, exiting...");
+                const QString errorMessage = QCoreApplication::translate("Main", "Error when daemonizing. Reason: \"%1\". Error code: %2.")
+                    .arg(QString::fromLocal8Bit(strerror(errno)), QString::number(errno));
+                LogMsg(errorMessage, Log::CRITICAL);
+                qCritical("%s", qUtf8Printable(errorMessage));
                 return EXIT_FAILURE;
             }
         }

src/base/utils/os.cpp

@@ -31,8 +31,6 @@
 #include "os.h"
 
 #ifdef Q_OS_WIN
-#include <memory>
-
 #include <windows.h>
 #include <powrprof.h>
 #include <shlobj.h>
@@ -87,11 +85,9 @@ void Utils::OS::shutdownComputer([[maybe_unused]] const ShutdownDialogAction &ac
     }
     else
     {
-        const QString msg = QCoreApplication::translate("misc"
+        std::wstring msg = QCoreApplication::translate("misc"
-            , "qBittorrent will shutdown the computer now because all downloads are complete.");
+            , "qBittorrent will shutdown the computer now because all downloads are complete.").toStdWString();
-        auto msgWchar = std::make_unique<wchar_t[]>(msg.length() + 1);
+        ::InitiateSystemShutdownW(nullptr, msg.data(), 10, TRUE, FALSE);
-        msg.toWCharArray(msgWchar.get());
-        ::InitiateSystemShutdownW(nullptr, msgWchar.get(), 10, TRUE, FALSE);
     }
 
     // Disable shutdown privilege.