Fixing the issue where multi-byte characters are split in writeCData() if first byte sits right at the end of the buffer (#87)

Author: tatsel

src/main/java/com/fasterxml/aalto/out/ByteXmlWriter.java

@@ -792,6 +792,13 @@ public int writeCData(char[] cbuf, int offset, int len)
     protected int writeCDataContents(char[] cbuf, int offset, int len)
         throws IOException, XMLStreamException
     {
+        if (_surrogate != 0) {
+            outputSurrogates(_surrogate, cbuf[offset]);
+//           reset the temporary surrogate storage
+            _surrogate = 0;
+            ++offset;
+            --len;
+        }
         /* Unlike with writeCharacters() and fastWriteName(), let's not
          * worry about split buffers here: this is unlikely to become
          * performance bottleneck. This allows keeping it simple; and

src/test/java/com/fasterxml/aalto/sax/TestSaxWriter.java

@@ -54,4 +54,29 @@ public void testSurrogateMemory2() throws Exception {
         writer.writeEndTag(writer.constructName("testelement"));
         writer.close(false);
     }
+
+    public void testSurrogateMemory3() throws Exception {
+        // This test aims to produce the
+        // javax.xml.stream.XMLStreamException: Incomplete surrogate pair in content: first char 0xdfce, second 0x78
+        // error message. The issue was similar to the one described in testSurrogateMemory1(), except it happened in
+        // ByteXmlWriter#writeCDataContents(), where check for existing _surrogate was missing prior to the fix,
+        // as opposed to ByteXmlWriter#writeCharacters().
+        StringBuilder testText = new StringBuilder();
+        for (int i = 0; i < 511; i++)
+            testText.append('x');
+        testText.append("\uD835\uDFCE");
+        for (int i = 0; i < 512; i++)
+            testText.append('x');
+
+        WriterConfig writerConfig = new WriterConfig();
+        ByteArrayOutputStream byteArrayOutputStream = new ByteArrayOutputStream();
+        Utf8XmlWriter writer = new Utf8XmlWriter(writerConfig, byteArrayOutputStream);
+        writer.writeStartTagStart(writer.constructName("testelement"));
+        writer.writeCData(testText.toString());
+        writer.writeStartTagEnd();
+        writer.writeEndTag(writer.constructName("testelement"));
+        writer.close(false);
+
+    }
+
 }