cabana: properly handle unix signals (#28657)

old-commit-hash: fe91ea1139

tools/cabana/cabana.cc

@@ -15,6 +15,8 @@ int main(int argc, char *argv[]) {
   QApplication app(argc, argv);
   app.setApplicationDisplayName("Cabana");
   app.setWindowIcon(QIcon(":cabana-icon.png"));
+
+  UnixSignalHandler signalHandler;
   utils::setTheme(settings.theme);
 
   QCommandLineParser cmd_parser;

tools/cabana/util.cc

@@ -1,7 +1,11 @@
 #include "tools/cabana/util.h"
 
 #include <array>
+#include <csignal>
+#include <sys/socket.h>
+#include <unistd.h>
 
+#include <QDebug>
 #include <QColor>
 #include <QFontDatabase>
 #include <QLocale>
@@ -145,6 +149,40 @@ void TabBar::closeTabClicked() {
   }
 }
 
+// UnixSignalHandler
+
+UnixSignalHandler::UnixSignalHandler(QObject *parent) : QObject(nullptr) {
+  if (::socketpair(AF_UNIX, SOCK_STREAM, 0, sig_fd)) {
+    qFatal("Couldn't create TERM socketpair");
+  }
+
+  sn = new QSocketNotifier(sig_fd[1], QSocketNotifier::Read, this);
+  connect(sn, SIGNAL(activated(QSocketDescriptor)), this, SLOT(handleSigTerm()));
+  std::signal(SIGINT, signalHandler);
+  std::signal(SIGTERM, UnixSignalHandler::signalHandler);
+}
+
+UnixSignalHandler::~UnixSignalHandler() {
+  ::close(sig_fd[0]);
+  ::close(sig_fd[1]);
+}
+
+void UnixSignalHandler::signalHandler(int s) {
+  ::write(sig_fd[0], &s, sizeof(s));
+}
+
+void UnixSignalHandler::handleSigTerm() {
+  sn->setEnabled(false);
+  int tmp;
+  ::read(sig_fd[1], &tmp, sizeof(tmp));
+
+  printf("\nexiting...\n");
+  qApp->closeAllWindows();
+  qApp->exit();
+}
+
+// NameValidator
+
 NameValidator::NameValidator(QObject *parent) : QRegExpValidator(QRegExp("^(\\w+)"), parent) {}
 
 QValidator::State NameValidator::validate(QString &input, int &pos) const {

tools/cabana/util.h

@@ -8,6 +8,7 @@
 #include <QDoubleValidator>
 #include <QFont>
 #include <QRegExpValidator>
+#include <QSocketNotifier>
 #include <QStringBuilder>
 #include <QStyledItemDelegate>
 #include <QToolButton>
@@ -135,5 +136,21 @@ private:
   void closeTabClicked();
 };
 
+class UnixSignalHandler : public QObject {
+  Q_OBJECT
+
+public:
+  UnixSignalHandler(QObject *parent = nullptr);
+  ~UnixSignalHandler();
+  static void signalHandler(int s);
+
+public slots:
+  void handleSigTerm();
+
+private:
+  inline static int sig_fd[2] = {};
+  QSocketNotifier *sn;
+};
+
 int num_decimals(double num);
 QString signalToolTip(const cabana::Signal *sig);