tdf#115429 sax: assert if exporting an invalid XML attribute/element

Add a cheap check for this in both SaxWriter and FastSaxSerializer
so we can find such bugs earlier, e.g. with the weekly crashtesting.

Don't do a correct check but a cheap & fast one, let's ignore
non-ASCII characters for now as the only filter with such is UOF
and that is implemented with XSLT, not this sax code.

Change-Id: I4db8f70ffb23684d4cb4211468519edd6c7c465f
Reviewed-on: https://gerrit.libreoffice.org/50507
Tested-by: Jenkins <ci@libreoffice.org>
Reviewed-by: Michael Stahl <mstahl@redhat.com>

1 files changed, 11 insertions, 4 deletions

diff --git a/sax/source/tools/fastserializer.cxx b/sax/source/tools/fastserializer.cxx
index 6257853a64a8..9356f3e081d1 100644
--- a/sax/source/tools/fastserializer.cxx
+++ b/sax/source/tools/fastserializer.cxx
@@ -270,11 +270,18 @@ namespace sax_fastparser {
     void FastSaxSerializer::writeId( ::sal_Int32 nElement )
     {
         if( HAS_NAMESPACE( nElement ) ) {
-            writeBytes(mxFastTokenHandler->getUTF8Identifier(NAMESPACE(nElement)));
+            auto const Namespace(mxFastTokenHandler->getUTF8Identifier(NAMESPACE(nElement)));
+            assert(Namespace.getLength() != 0);
+            writeBytes(Namespace);
             writeBytes(sColon, N_CHARS(sColon));
-            writeBytes(mxFastTokenHandler->getUTF8Identifier(TOKEN(nElement)));
-        } else
-            writeBytes(mxFastTokenHandler->getUTF8Identifier(nElement));
+            auto const Element(mxFastTokenHandler->getUTF8Identifier(TOKEN(nElement)));
+            assert(Element.getLength() != 0);
+            writeBytes(Element);
+        } else {
+            auto const Element(mxFastTokenHandler->getUTF8Identifier(nElement));
+            assert(Element.getLength() != 0);
+            writeBytes(Element);
+        }
     }
 
 #ifdef DBG_UTIL