Windows: improve error reporting if Conditional File Access is active

src/downloadextractthread.cpp

@@ -167,8 +167,7 @@ void DownloadExtractThread::extractImageRun()
                 {
                     if (!_cancelled)
                     {
-                        DownloadThread::cancelDownload();
+                        _onWriteError();
-                        emit error(tr("Error writing to storage"));
                     }
                     archive_read_free(a);
                     return;

src/downloadthread.cpp

@@ -444,23 +444,7 @@ void DownloadThread::run()
             break;
         case CURLE_WRITE_ERROR:
             deleteDownloadedFile();
-
+            _onWriteError();
-#ifdef Q_OS_WIN
-            if (_file.errorCode() == ERROR_ACCESS_DENIED)
-            {
-                QString msg = tr("Access denied error while writing file to disk.");
-                QSettings registry("HKEY_LOCAL_MACHINE\\SOFTWARE\\Microsoft\\Windows Defender\\Windows Defender Exploit Guard\\Controlled Folder Access",
-                                   QSettings::Registry64Format);
-                if (registry.value("EnableControlledFolderAccess").toInt() == 1)
-                {
-                    msg += "<br>"+tr("Controlled Folder Access seems to be enabled. Please add both rpi-imager.exe and fat32format.exe to the list of allowed apps and try again.");
-                }
-                _onDownloadError(msg);
-            }
-            else
-#endif
-            if (!_cancelled)
-                _onDownloadError(tr("Error writing file to disk"));
             break;
         case CURLE_ABORTED_BY_CALLBACK:
             deleteDownloadedFile();
@@ -671,6 +655,26 @@ void DownloadThread::_onDownloadError(const QString &msg)
     emit error(msg);
 }
 
+void DownloadThread::_onWriteError()
+{
+#ifdef Q_OS_WIN
+    if (_file.errorCode() == ERROR_ACCESS_DENIED)
+    {
+        QString msg = tr("Access denied error while writing file to disk.");
+        QSettings registry("HKEY_LOCAL_MACHINE\\SOFTWARE\\Microsoft\\Windows Defender\\Windows Defender Exploit Guard\\Controlled Folder Access",
+                           QSettings::Registry64Format);
+        if (registry.value("EnableControlledFolderAccess").toInt() == 1)
+        {
+            msg += "<br>"+tr("Controlled Folder Access seems to be enabled. Please add both rpi-imager.exe and fat32format.exe to the list of allowed apps and try again.");
+        }
+        _onDownloadError(msg);
+    }
+    else
+#endif
+    if (!_cancelled)
+        _onDownloadError(tr("Error writing file to disk"));
+}
+
 void DownloadThread::_closeFiles()
 {
     _file.close();

src/downloadthread.h

@@ -141,6 +141,7 @@ protected:
     virtual void run();
     virtual void _onDownloadSuccess();
     virtual void _onDownloadError(const QString &msg);
+    virtual void _onWriteError();
 
     void _hashData(const char *buf, size_t len);
     void _writeComplete();