Backport code to read database public headers

This is required to show the public icon, color, and name of a locked database

src/format/KdbxReader.cpp

@@ -55,6 +55,8 @@ bool KdbxReader::readMagicNumbers(QIODevice* device, quint32& sig1, quint32& sig
  * Read KDBX stream from device.
  * The device will automatically be reset to 0 before reading.
  *
+ * Passing a null key will only read in the unprotected headers.
+ *
  * @param device input device
  * @param key database encryption composite key
  * @param db database to read into
@@ -91,6 +93,11 @@ bool KdbxReader::readDatabase(QIODevice* device, QSharedPointer<const CompositeK
         return false;
     }
 
+    // No key provided - don't proceed to load payload
+    if (key.isNull()) {
+        return true;
+    }
+
     // read payload
     return readDatabaseImpl(device, headerStream.storedData(), std::move(key), db);
 }

src/gui/DatabaseOpenWidget.cpp

@@ -242,6 +242,12 @@ void DatabaseOpenWidget::load(const QString& filename)
     clearForms();
 
     m_filename = filename;
+    
+    // Read public headers
+    QString error;
+    m_db.reset(new Database());
+    m_db->open(m_filename, nullptr, &error);
+
     m_ui->fileNameLabel->setRawText(m_filename);
 
     // Set the public name if defined
@@ -296,7 +302,9 @@ void DatabaseOpenWidget::clearForms()
     toggleHardwareKeyComponent(false);
     toggleQuickUnlockScreen();
 
-    m_db.reset(new Database(m_filename));
+    QString error;
+    m_db.reset(new Database());
+    m_db->open(m_filename, nullptr, &error);
 }
 
 QSharedPointer<Database> DatabaseOpenWidget::database()
@@ -361,6 +369,8 @@ void DatabaseOpenWidget::openDatabase()
             msgBox->exec();
             if (msgBox->clickedButton() != btn) {
                 m_db.reset(new Database());
+                m_db->open(m_filename, nullptr, &error);
+
                 m_ui->messageWidget->showMessage(tr("Database unlock canceled."), MessageWidget::MessageType::Error);
                 setUserInteractionLock(false);
                 return;