fix(helper): disconnect QProcess::finished signal when received

ItsShamed · ItsShamed · commit 7522be5a24a1 · 2025-07-30T17:44:26.000+02:00
… and handle the undefiend behavior.

We are going to exit anyway, so we must avoid receiving extra signals
that may interfere while exiting, as those may as well originate from
undefined behavior found in Qt Base…

Signed-off-by: tsrk. &lt;tsrk@tsrk.me&gt;
diff --git a/src/helper/HelperApp.cpp b/src/helper/HelperApp.cpp
@@ -199,14 +199,25 @@ namespace SDDM {
     }
 
     void HelperApp::sessionFinished(int exitCode, QProcess::ExitStatus exitStatus) {
+        disconnect(m_session, QOverload<int, QProcess::ExitStatus>::of(&QProcess::finished), this, &HelperApp::sessionFinished);
         if (exitStatus == QProcess::NormalExit) {
             if (exitCode != 0) {
                 qWarning("Session crashed (exit code %d).", exitCode);
                 exit(Auth::HELPER_SESSION_ERROR);
             }
             else
                 exit(Auth::HELPER_SUCCESS);
+            return;
+        }
+
+        // Crashing with 0 is impossible, since UNIX signals start at 1…
+        // …unless we reached an undefined behavior.
+        if (exitCode == 0) {
+            qCritical() << "Qt reached an undefined behavior. This should be reported to Qt, but will be ignored for the time being.";
+            exit(Auth::HELPER_SUCCESS);
+            return;
         }
+
         qWarning("Session crashed (killed by signal %d).", exitCode);
         exit(Auth::HELPER_SESSION_ERROR);
     }
