Protect epi/gpi_storeHW/SWVer() by a mutex (guard)

include/hwapi.h

@@ -121,8 +121,13 @@ public:
     explicit hwapi(QObject *parent = nullptr);
 
 
+
     #ifdef  THIS_IS_CA_MASTER
-    T_datif *myDatif;
+        T_datif *myDatif;
+    #else // THIS_IS_CA_SLAVE
+        QString getVersions();
+        void resetVersions();
+        bool m_resetVersions = false;
     #endif
 
     T_runProc *runProcess;
@@ -1401,6 +1406,8 @@ public:
 
 
 signals:
+    void hwapi_restoredVersions();
+
     void hwapi_reportDCDownloadStatus(QString const&) const override;
     void hwapi_reportDCDownloadSuccess(QString const&) const override;
     void hwapi_reportDCDownloadFailure(QString const&) const override;

src/hwapi.cpp

@@ -11,6 +11,7 @@
 #include "hwapi.h"
 #include "download_thread.h"
 #include "reporting_thread.h"
+#include "storeINdata.h" // epi_loadSWVer, epi_loadHWVer
 
 #include <cstring>
 #include <QThread>
@@ -25,6 +26,37 @@ static uint8_t  hwapi_lastDoorState;
 static uint8_t bl_startupStep;
 
 
+#ifdef THIS_IS_CA_MASTER
+#else // THIS_IS_CA_SLAVE
+    QString hwapi::getVersions() {
+        if (m_sharedMem != nullptr) {
+             // check if sw/hw-versions have been restored (see resetVersions()).
+             // emit a signal in such a case.
+             QString const &sw = epi_loadSWver(); // command 11
+             QString const &hw = epi_loadHWver(); // command 12
+             if (!sw.isEmpty() && !hw.isEmpty() && m_resetVersions) {
+                emit hwapi_restoredVersions();
+                return sw + " " + hw;
+             }
+        }
+        return "";
+    }
+
+    void hwapi::resetVersions() {
+        if (m_sharedMem != nullptr) {
+             // command 11 and 12 are included in the requests sent automatically,
+             // first 11, then 12. The results are used to refresh corresponding
+             // shared memory locations.
+             // set these locations to the empty string in the opposite order as
+             // the commands are sent.
+             // purpose: only when both locations are not empty again, we can be
+             // sure that data are not obsolete.
+             gpi_storeHWver(""); // command 12
+             gpi_storeSWver(""); // command 11
+             m_resetVersions = true;
+        }
+    }
+#endif
 
 hwapi::hwapi(QObject *parent) : QObject(parent)
 {

src/storeINdata.cpp

@@ -6,6 +6,11 @@
 #include "shared_mem_buffer.h"
 #include "datei.h"
 
+#include <QMutex>
+#include <QMutexLocker>
+
+static QMutex SWHD_mutex;
+
 // gpi: grafical access to PI: access from external devices over device controller FOR GUI
 // epi: external access from GUI to PI:  FOR external devices (DC)
 
@@ -64,6 +69,7 @@ bool indat_isMdbOn()
 
 void gpi_storeHWver(QString text)
 {
+    QMutexLocker locker(&SWHD_mutex);
     // change Qstring to array of chars, because shared mem allowes no QString!
     int  nn, LL = text.length();
     if (LL >= versionBufferLen)
@@ -79,6 +85,7 @@ void gpi_storeHWver(QString text)
 
 QString epi_loadHWver(void)
 {
+    QMutexLocker locker(&SWHD_mutex);
     // load array of chars from SM and change to QString
     int  nn, LL = versionBufferLen;
     char cc;
@@ -96,6 +103,7 @@ QString epi_loadHWver(void)
 
 void gpi_storeSWver(QString text)
 {    
+    QMutexLocker locker(&SWHD_mutex);
     int  nn, LL = text.length();
     if (LL >= versionBufferLen)
         LL=versionBufferLen-1;   // leave place for termination
@@ -111,6 +119,7 @@ void gpi_storeSWver(QString text)
 
 QString epi_loadSWver(void)
 {
+    QMutexLocker locker(&SWHD_mutex);
     int  nn, LL = versionBufferLen;
     char cc;
     QString myStr;