- dont overwrite an invalid settings file in any case

- fix file writing

ScStwLibraries/headers/scstwsettings.h

@@ -34,7 +34,7 @@ class ScStwSettings : public QObject
 {
     Q_OBJECT
 public:
-    explicit ScStwSettings(QObject *parent = nullptr);
+    explicit ScStwSettings(QObject *parent = nullptr, bool overwriteFileOnErrors = true);
 
     typedef QString(*keyToStringConverter)(int);
     typedef QVariant::Type(*keyToTypeConverter)(int);
@@ -104,6 +104,8 @@ protected:
     bool registerKeyLevelConverters(int keyLevel, keyToStringConverter, keyToTypeConverter);
 
 private:
+    bool fileIsReadonly;
+
     QFile * settingsFile;
     QVariantMap settingsCache;
 

ScStwLibraries/sources/scstwsettings.cpp

@@ -18,7 +18,7 @@
 
 #include "../headers/scstwsettings.h"
 
-ScStwSettings::ScStwSettings(QObject *parent) : QObject(parent)
+ScStwSettings::ScStwSettings(QObject *parent, bool overwriteFileOnErrors) : QObject(parent)
 {
 #ifdef RASPI
     QString path = "/root/.config/ScStwBasestation";
@@ -30,14 +30,21 @@ ScStwSettings::ScStwSettings(QObject *parent) : QObject(parent)
         qFatal("[FATAL] Failed to create writable directory for settings at %s", qPrintable(path));
 
     this->settingsFile = new QFile(path + "/settings.json");
+    this->fileIsReadonly = false;
 
     if(!this->settingsFile->open(QFile::ReadWrite))
         qFatal("[FATAL] Couldn't open settings file %s", qPrintable(path + "/settings.json"));
 
-    if(!this->loadSettingsFromFile() && this->settingsFile->size() != 0) {
+    if(this->settingsFile->size() != 0 && !this->loadSettingsFromFile()) {
+        if(overwriteFileOnErrors) {
             this->writeSettingsToFile();
             qWarning("[WARNING] Settings file (%s) was of invalid format and therefore overwritten!", qPrintable(path + "/settings.json"));
         }
+        else {
+            qWarning("[WARNING] Settings file (%s) was of invalid format!", qPrintable(path + "/settings.json"));
+            this->fileIsReadonly = true;
+        }
+    }
 
     connect(this, &ScStwSettings::settingChanged, this, &ScStwSettings::writeSettingsToFile);
 
@@ -144,9 +151,15 @@ bool ScStwSettings::registerKeyLevelConverters(int keyLevel, keyToStringConverte
  */
 
 bool ScStwSettings::writeSettingsToFile() {
+    if(this->fileIsReadonly) {
+        qWarning() << "[WARNING][SETTINS] Cannot write changes to file! It has been marked readonly due to parse errors (see above).";
+        return false;
+    }
+
     QJsonDocument doc = QJsonDocument::fromVariant(this->settingsCache);
 
     // overwrite file
+    this->settingsFile->resize(0);
     this->settingsFile->reset();
     this->settingsFile->write(doc.toJson(QJsonDocument::Indented));
     this->settingsFile->flush();
@@ -155,7 +168,13 @@ bool ScStwSettings::writeSettingsToFile() {
 }
 
 bool ScStwSettings::loadSettingsFromFile() {
-    QJsonDocument doc = QJsonDocument::fromJson(this->settingsFile->readAll());
+    QJsonParseError error;
+    QJsonDocument doc = QJsonDocument::fromJson(this->settingsFile->readAll(), &error);
+
+    if(error.error != QJsonParseError::NoError) {
+        qWarning() << "[ERROR][SETTINGS] Error when parsing settings file: " << error.errorString() << " at offset " << error.offset;
+        return false;
+    }
 
     if(doc.toVariant().type() != QVariant::Map)
         return false;