dbaccess: don't try to migrate read-only file

It's going to throw IOException anyway.

This fixes CppunitTest_dbaccess_hsqldb_test on read-only file system.

Change-Id: Ifc8a4791ab9a1a8d3e0f1e67d65e10dac458147c
Reviewed-on: https://gerrit.libreoffice.org/67028
Tested-by: Jenkins
Reviewed-by: Michael Stahl <Michael.Stahl@cib.de>

dbaccess/source/core/dataaccess/datasource.cxx

@@ -605,6 +605,7 @@ Reference< XConnection > ODatabaseSource::buildLowLevelConnection(const OUString
     bool bNeedMigration = false;
     if(m_pImpl->m_sConnectURL == "sdbc:embedded:hsqldb")
     {
+        Reference<XStorage> const xRootStorage = m_pImpl->getOrCreateRootStorage();
         OUString sMigrEnvVal;
         osl_getEnvironment(OUString("DBACCESS_HSQL_MIGRATION").pData,
             &sMigrEnvVal.pData);
@@ -612,14 +613,18 @@ Reference< XConnection > ODatabaseSource::buildLowLevelConnection(const OUString
             bNeedMigration = true;
         else
         {
-            MigrationWarnDialog aWarnDlg(GetFrameWeld(m_pImpl->getModel_noCreate()));
-            bNeedMigration = aWarnDlg.run() == RET_OK;
+            Reference<XPropertySet> const xPropSet(xRootStorage, UNO_QUERY_THROW);
+            sal_Int32 nOpenMode(0);
+            if ((xPropSet->getPropertyValue("OpenMode") >>= nOpenMode)
+                && (nOpenMode & css::embed::ElementModes::WRITE))
+            {
+                MigrationWarnDialog aWarnDlg(GetFrameWeld(m_pImpl->getModel_noCreate()));
+                bNeedMigration = aWarnDlg.run() == RET_OK;
+            }
         }
         if (bNeedMigration)
         {
             // back up content xml file if migration was successful
-            Reference<XStorage> xRootStorage = m_pImpl->getOrCreateRootStorage();
-
             constexpr char BACKUP_XML_NAME[] = "content_before_migration.xml";
             try
             {