Fix warnings calling system in callbacks without checking the result. For that task the wrapper Util::systemWithMessage was created.

src/control/pagetype/PageTypeHandler.cpp

@@ -145,4 +145,5 @@ auto PageTypeHandler::getStringForPageTypeFormat(const PageTypeFormat& format) -
         case PageTypeFormat::Copy:
             return ":copy";
     }
+    return "ruled";
 }

src/gui/dialog/SettingsDialog.cpp

@@ -36,12 +36,12 @@ SettingsDialog::SettingsDialog(GladeSearchpath* gladeSearchPath, Settings* setti
 
 
     g_signal_connect(get("btTestEnable"), "clicked", G_CALLBACK(+[](GtkButton* bt, SettingsDialog* self) {
-                         system(gtk_entry_get_text(GTK_ENTRY(self->get("txtEnableTouchCommand"))));
+                         Util::systemWithMessage(gtk_entry_get_text(GTK_ENTRY(self->get("txtEnableTouchCommand"))));
                      }),
                      this);
 
     g_signal_connect(get("btTestDisable"), "clicked", G_CALLBACK(+[](GtkButton* bt, SettingsDialog* self) {
-                         system(gtk_entry_get_text(GTK_ENTRY(self->get("txtDisableTouchCommand"))));
+                         Util::systemWithMessage(gtk_entry_get_text(GTK_ENTRY(self->get("txtDisableTouchCommand"))));
                      }),
                      this);
 

src/gui/inputdevices/touchdisable/TouchDisableCustom.cpp

@@ -2,11 +2,14 @@
 
 #include <utility>
 
+#include "Util.h"
+
+
 TouchDisableCustom::TouchDisableCustom(string enableCommand, string disableCommand):
         enableCommand(std::move(enableCommand)), disableCommand(std::move(disableCommand)) {}
 
 TouchDisableCustom::~TouchDisableCustom() = default;
 
-void TouchDisableCustom::enableTouch() { system(enableCommand.c_str()); }
+void TouchDisableCustom::enableTouch() { Util::systemWithMessage(enableCommand.c_str()); }
 
-void TouchDisableCustom::disableTouch() { system(disableCommand.c_str()); }
+void TouchDisableCustom::disableTouch() { Util::systemWithMessage(disableCommand.c_str()); }

src/gui/inputdevices/touchdisable/TouchDisableGdk.cpp

@@ -21,6 +21,8 @@ void TouchDisableGdk::enableTouch() {
 
     gtk_grab_remove(this->widget);
     // Todo(@ulrich): replace this with gdk_device_ungrab
+    //                but gdk_device_ungrab is deprecated too, since GTK 3.20
+    //                gtk_seat_ungrab has to be used instead,
     gdk_pointer_ungrab(GDK_CURRENT_TIME);  // NOLINT
 }
 
@@ -34,7 +36,9 @@ void TouchDisableGdk::disableTouch() {
      * See the following link if window dragging by double clicks on empty widget space occurs
      * https://www.reddit.com/r/kde/comments/aaeo91
      */
-    // Todo(@ulrich): replace this with gdk_device_ungrab
+    // Todo(@ulrich): replace this with gdk_device_grab
+    //                but gdk_device_grab is deprecated too, since GTK 3.20
+    //                gtk_seat_grab has to be used instead,
     gdk_pointer_grab(window, false, GDK_TOUCH_MASK, nullptr, nullptr, GDK_CURRENT_TIME);  // NOLINT
     gtk_grab_add(this->widget);
 }

src/util/Util.cpp

@@ -1,6 +1,7 @@
 #include "Util.h"
 
 #include <array>
+#include <cstdlib>
 #include <utility>
 
 #include <unistd.h>
@@ -160,3 +161,10 @@ void Util::writeCoordinateString(OutputStream* out, double xVal, double yVal) {
     g_ascii_formatd(coordString.data(), G_ASCII_DTOSTR_BUF_SIZE, Util::PRECISION_FORMAT_STRING, yVal);
     out->write(coordString.data());
 }
+
+void Util::systemWithMessage(const char* command) {
+    if (auto errc = std::system(command); errc != 0) {
+        string msg = FS(_F("Error {1} executing system command: {2}") % errc % command);
+        XojMsgBox::showErrorToUser(nullptr, msg);
+    }
+}

src/util/Util.h

@@ -44,6 +44,11 @@ Path getTmpDirSubfolder(const Path& subfolder = "");
 
 Path ensureFolderExists(const Path& p);
 
+/**
+ * Wrap the system call to redirect errors to a dialog
+ */
+void systemWithMessage(const char* command);
+
 /**
  * Execute the callback in the UI Thread.
  *

test/SpeedTest.cpp

@@ -50,6 +50,8 @@ private:
     static void printMemory() {
         string cmd = "bash -c \"cat /proc/";
         cmd += std::to_string(::getpid()) + "/status | grep Vm\"";
-        system(cmd.c_str());
+        if (system(cmd.c_str()) != 0) {
+            cout << "Error executing " << cmd.c_str() << endl;
+        };
     }
 };