Fix #91: handle split-buffary surrogate for comments as well

Author: cowtowncoder

release-notes/VERSION

@@ -6,10 +6,12 @@ Project: aalto-xml
 
 1.3.3 (not yet released)
 
-#86: Multi-byte characters are split in writeCData() if first byte sits
+#86: Multi-byte characters are split in `writeCData()` if first byte sits
   right at the end of the buffer
  (reported, fix contributed by @tatsel)
 #90: Update stax2-api dep to 4.2.2 (from 4.2)
+#91: Multi-byte characters are split in `writeComment()` if first byte sits
+  right at the end of the buffer
 
 1.3.2 (25-Apr-2022)
 

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

@@ -799,6 +799,7 @@ protected int writeCDataContents(char[] cbuf, int offset, int len)
             ++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
@@ -1197,12 +1198,18 @@ public int writeComment(String data) throws IOException, XMLStreamException
     protected int writeCommentContents(char[] cbuf, int offset, int len)
         throws IOException, XMLStreamException
     {
-        /* 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
-         * should it matter, we could start doing fast version here
-         * as well.
-         */
+        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
+        // should it matter, we could start doing fast version here as well.
         len += offset; // now marks the end
 
         main_loop:

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

@@ -60,11 +60,7 @@ public void testSplitSurrogateWithAttributeValue2() throws Exception
 
     public void testSplitSurrogateWithCData() 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().
+        // Modification of "testSplitSurrogateWithAttributeValue()" but for CDATA
         StringBuilder testText = new StringBuilder();
         for (int i = 0; i < 511; i++) {
             testText.append('x');
@@ -83,4 +79,27 @@ public void testSplitSurrogateWithCData() throws Exception
         writer.writeEndTag(writer.constructName("testelement"));
         writer.close(false);
     }
+
+
+    public void testSplitSurrogateWithComment() throws Exception
+    {
+        // Modification of "testSplitSurrogateWithAttributeValue()" but for Comment
+        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.writeComment(testText.toString());
+        writer.writeStartTagEnd();
+        writer.writeEndTag(writer.constructName("testelement"));
+        writer.close(false);
+    }
 }