Clean termination on *nix systems

SMSubProcess.cpp

@@ -67,16 +67,31 @@ void SMSubProcess::processError(QProcess::ProcessError error)
     }
 }
 
+void SMSubProcess::aboutToQuit()
+{
+    // Main process terminated
+    if (process.state() == QProcess::Running) {
+        process.terminate();
+        if (!process.waitForFinished(60000)) {
+            QTextStream(stderr) << "Failed to terminate process!" << endl;
+        }
+    }
+}
+
 void SMSubProcess::killProcess()
 {
     // Kill process as requested
+    if (process.state() == QProcess::Running) {
         process.kill();
+    }
 }
 
 void SMSubProcess::stopProcess()
 {
     // Terminate process as requested
+    if (process.state() == QProcess::Running) {
         process.terminate();
+    }
 }
 
 void SMSubProcess::writeInput(const QByteArray &input)

SMSubProcess.h

@@ -33,6 +33,7 @@ private:
     QProcess process;
 
 public slots:
+    void aboutToQuit();
     void killProcess();
     void stopProcess();
     void writeInput(const QByteArray &input);

main.cpp

@@ -30,12 +30,44 @@
 #include "SMSubServer.h"
 #include "smsub.h"
 
+#ifdef Q_OS_UNIX
+#include <initializer_list>
+#include "signal.h"
+#include "unistd.h"
+#endif
+
+#ifdef Q_OS_UNIX
+void catchUnixSignals(std::initializer_list<int> quitSignals) {
+    auto handler = [](int sig) -> void {
+        QTextStream(stderr) << "Received Unix signal: " << sig << endl;
+        QCoreApplication::quit();
+    };
+
+    sigset_t blocking_mask;
+    sigemptyset(&blocking_mask);
+    for (auto sig : quitSignals)
+        sigaddset(&blocking_mask, sig);
+
+    struct sigaction sa;
+    sa.sa_handler = handler;
+    sa.sa_mask    = blocking_mask;
+    sa.sa_flags   = 0;
+
+    for (auto sig : quitSignals)
+        sigaction(sig, &sa, nullptr);
+}
+#endif
+
 int main(int argc, char *argv[])
 {
     QCoreApplication a(argc, argv);
     a.setApplicationName("Server Manager Subprocess");
     a.setApplicationVersion("0.1");
 
+#ifdef Q_OS_UNIX
+    catchUnixSignals({SIGQUIT, SIGINT, SIGTERM, SIGHUP});
+#endif
+
     QCommandLineParser commandLineParser;
     commandLineParser.addHelpOption();
     commandLineParser.addVersionOption();
@@ -148,6 +180,7 @@ int main(int argc, char *argv[])
     QObject::connect(&subServer, SIGNAL(inputWritten(QByteArray)), &subProcess, SLOT(writeInput(QByteArray)));
     QObject::connect(&subServer, SIGNAL(killRequested()), &subProcess, SLOT(killProcess()));
     QObject::connect(&subServer, SIGNAL(stopRequested()), &subProcess, SLOT(stopProcess()));
+    QObject::connect(&a, SIGNAL(aboutToQuit()), &subProcess, SLOT(aboutToQuit()));
 
     subProcess.start();