Adding shared memory containing all variables necessary to

check device controller related variables.

src/shared_mem_buffer.cpp

@@ -0,0 +1,39 @@
+#include "shared_mem_buffer.h"
+
+#include <QDebug>
+#include <atomic>
+
+#ifdef QT_POSIX_IPC
+    // The POSIX backend can be explicitly selected using the -feature-ipc_posix
+    // option to the Qt configure script. If it is enabled, the QT_POSIX_IPC
+    // macro will be defined. -> we use SystemV shared memory
+#error "QT_POSIX_IPC defined"
+#else
+#include <sys/ipc.h>    // ftok
+#endif
+
+// std::atomic_bool SharedMemBuffer::__sharedMemLocked{false};
+
+QSharedMemory *SharedMemBuffer::getShm(std::size_t size) {
+    static QSharedMemory shMem;
+    if (size > 0) {
+        static const long nativeKey = ftok("/etc/os-release", 'H');
+        static const QString fkey = std::to_string(nativeKey).c_str();
+        shMem.setKey(fkey);
+        if (!shMem.isAttached()) {
+            if (shMem.create(size)) {
+                return &shMem;
+            } else {
+                if (shMem.error() == QSharedMemory::AlreadyExists) {
+                    if (shMem.attach()) {
+                        return &shMem;
+                    }
+                }
+            }
+            qCritical() << shMem.nativeKey() << shMem.key() << shMem.data()
+                        << shMem.error() << shMem.errorString();
+            return nullptr;
+        }
+    }
+    return &shMem;
+}