Adapt to Qt6 QProcess::setChildProcessModifier()

Qt5 QProcess::setupChildProcess() was removed.
Based on KDE KPty commit d429116888921814c01a57ba4ef0144a25fd33ec

It keeps sync with upstream code.

lib/Pty.cpp

@@ -271,6 +271,26 @@ Pty::Pty(QObject* parent)
 }
 void Pty::init()
 {
+    // Must call parent class child process modifier, as it sets file descriptors ...etc
+    auto parentChildProcModifier = KPtyProcess::childProcessModifier();
+    setChildProcessModifier([parentChildProcModifier = std::move(parentChildProcModifier)]() {
+        if (parentChildProcModifier) {
+            parentChildProcModifier();
+    }
+
+    // reset all signal handlers
+    // this ensures that terminal applications respond to
+    // signals generated via key sequences such as Ctrl+C
+    // (which sends SIGINT)
+    struct sigaction action;
+    sigemptyset(&action.sa_mask);
+    action.sa_handler = SIG_DFL;
+    action.sa_flags = 0;
+    for (int signal = 1; signal < NSIG; signal++) {
+        sigaction(signal, &action, nullptr);
+    }
+    });
+
   _windowColumns = 0;
   _windowLines = 0;
   _eraseChar = 0;
@@ -326,23 +346,3 @@ int Pty::foregroundProcessGroup() const
     return 0;
 }
 
-void Pty::onSetupChildProcess()
-{
-    KPtyProcess::onSetupChildProcess();
-
-    // reset all signal handlers
-    // this ensures that terminal applications respond to
-    // signals generated via key sequences such as Ctrl+C
-    // (which sends SIGINT)
-    struct sigaction action;
-    sigset_t sigset;
-    sigemptyset(&action.sa_mask);
-    sigemptyset(&sigset);
-    action.sa_handler = SIG_DFL;
-    action.sa_flags = 0;
-    for (int signal=1;signal < NSIG; signal++) {
-        sigaction(signal,&action,nullptr);
-        sigaddset(&sigset, signal);
-    }
-    sigprocmask(SIG_UNBLOCK, &sigset, nullptr);
-}

lib/Pty.h

@@ -188,9 +188,6 @@ Q_OBJECT
      */
     void receivedData(const char* buffer, int length);
 
-  protected:
-      void onSetupChildProcess() override;
-
   private slots:
     // called when data is received from the terminal process
     void dataReceived();

lib/kptyprocess.cpp

@@ -40,9 +40,6 @@
 KPtyProcess::KPtyProcess(QObject *parent) :
     KPtyProcess(-1, parent)
 {
-    setChildProcessModifier([this](){ 
-        onSetupChildProcess();
-    });
 }
 
 KPtyProcess::KPtyProcess(int ptyMasterFd, QObject *parent) :
@@ -51,6 +48,24 @@ KPtyProcess::KPtyProcess(int ptyMasterFd, QObject *parent) :
 {
     Q_D(KPtyProcess);
 
+    setChildProcessModifier([d]() {
+        d->pty->setCTty();
+#if 0
+        if (d->addUtmp) {
+            d->pty->login(KUser(KUser::UseRealUserID).loginName().toLocal8Bit().constData(), qgetenv("DISPLAY").constData());
+        }
+#endif
+        if (d->ptyChannels & StdinChannel) {
+            dup2(d->pty->slaveFd(), 0);
+        }
+        if (d->ptyChannels & StdoutChannel) {
+            dup2(d->pty->slaveFd(), 1);
+        }
+        if (d->ptyChannels & StderrChannel) {
+            dup2(d->pty->slaveFd(), 2);
+        }
+    });
+
     d->pty = std::make_unique<KPtyDevice>(this);
 
     if (ptyMasterFd == -1) {
@@ -124,24 +139,4 @@ KPtyDevice *KPtyProcess::pty() const
     return d->pty.get();
 }
 
-void KPtyProcess::onSetupChildProcess()
-{
-    Q_D(KPtyProcess);
-
-    d->pty->setCTty();
-
-#if 0
-    if (d->addUtmp)
-        d->pty->login(KUser(KUser::UseRealUserID).loginName().toLocal8Bit().data(), qgetenv("DISPLAY"));
-#endif
-    if (d->ptyChannels & StdinChannel)
-        dup2(d->pty->slaveFd(), 0);
-
-    if (d->ptyChannels & StdoutChannel)
-        dup2(d->pty->slaveFd(), 1);
-
-    if (d->ptyChannels & StderrChannel)
-        dup2(d->pty->slaveFd(), 2);
-}
-
 //#include "kptyprocess.moc"

lib/kptyprocess.h

@@ -142,10 +142,6 @@ class KPtyProcess : public KProcess
     KPtyDevice *pty() const;
 
 protected:
-    /**
-     * Child process configuration
-     */
-    virtual void onSetupChildProcess();
 
 private:
     std::unique_ptr<KPtyProcessPrivate> const d_ptr;