8291792: DefaultStyledDocument.setCharacterAttributes accepts negative length

Reviewed-by: psadhukhan, prr

src/java.desktop/share/classes/javax/swing/text/DefaultStyledDocument.java

@@ -484,6 +484,18 @@ public class DefaultStyledDocument extends AbstractDocument implements StyledDoc
      * A write lock is held by this operation while changes
      * are being made, and a DocumentEvent is sent to the listeners
      * after the change has been successfully completed.
+     *
+     * <p>
+     * {@code offset} and {@code length} define the range of the text
+     * over which the attributes are set.
+     * If the length is &lt;= 0, then no action is taken  and the method
+     * just returns.
+     * If the offset is &lt;=0 or &gt; the length of the text then no
+     * action is taken, and the method just returns.
+     * Otherwise if {@code offset + length} will exceed the length of
+     * the  text then the affected range is truncated.
+     * </p>
+     *
      * <p>
      * This method is thread safe, although most Swing methods
      * are not. Please see
@@ -491,13 +503,13 @@ public class DefaultStyledDocument extends AbstractDocument implements StyledDoc
      * in Swing</A> for more information.
      *
      * @param offset the offset in the document &gt;= 0
-     * @param length the length &gt;= 0
+     * @param length the length &gt; 0
      * @param s the attributes
      * @param replace true if the previous attributes should be replaced
      *  before setting the new attributes
      */
     public void setCharacterAttributes(int offset, int length, AttributeSet s, boolean replace) {
-        if (length == 0) {
+        if (length <= 0) {
             return;
         }
         try {

test/jdk/javax/swing/text/DefaultStyledDocument/DocNegLenCharAttrTest.java

@@ -0,0 +1,85 @@
+/*
+ * Copyright (c) 2022, Oracle and/or its affiliates. All rights reserved.
+ * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
+ *
+ * This code is free software; you can redistribute it and/or modify it
+ * under the terms of the GNU General Public License version 2 only, as
+ * published by the Free Software Foundation.
+ *
+ * This code is distributed in the hope that it will be useful, but WITHOUT
+ * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
+ * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
+ * version 2 for more details (a copy is included in the LICENSE file that
+ * accompanied this code).
+ *
+ * You should have received a copy of the GNU General Public License version
+ * 2 along with this work; if not, write to the Free Software Foundation,
+ * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
+ *
+ * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
+ * or visit www.oracle.com if you need additional information or have any
+ * questions.
+ */
+
+import java.awt.BorderLayout;
+import java.awt.Dimension;
+import java.lang.reflect.InvocationTargetException;
+
+import javax.swing.JFrame;
+import javax.swing.JLabel;
+import javax.swing.JTextPane;
+import javax.swing.SwingUtilities;
+import javax.swing.text.AttributeSet;
+import javax.swing.text.DefaultStyledDocument;
+import javax.swing.text.SimpleAttributeSet;
+import javax.swing.text.StyleConstants;
+
+/*
+ * @test
+ * @bug 8291792
+ * @key headful
+ * @summary Test to check if negative length check is implemented in
+ * setCharacterAttributes(). Test should not throw any exception on
+ * negative length.
+ * @run main DocNegLenCharAttrTest
+ */
+public class DocNegLenCharAttrTest {
+    private static JFrame frame;
+    public static void main(String[] args) throws InterruptedException, InvocationTargetException {
+        try {
+            SwingUtilities.invokeAndWait(new Runnable() {
+                public void run() {
+                    test();
+                }
+            });
+        } finally {
+            frame.dispose();
+        }
+        System.out.println("Test Pass!");
+    }
+
+    public static void test() {
+        DefaultStyledDocument doc;
+        frame = new JFrame();
+        doc = new DefaultStyledDocument();
+        JTextPane text = new JTextPane();
+        text.setDocument(doc);
+        text.setText("hello world");
+        doc.setCharacterAttributes(6, -5,
+                createLabelAttribute("world"), true);
+
+        frame.setPreferredSize(new Dimension(100,70));
+        frame.add(text);
+        frame.setLayout(new BorderLayout());
+        frame.add(text,BorderLayout.SOUTH);
+        frame.setVisible(true);
+        frame.pack();
+    }
+
+    private static AttributeSet createLabelAttribute(String text){
+        JLabel lbl = new JLabel(text.toUpperCase());
+        SimpleAttributeSet attr = new SimpleAttributeSet();
+        StyleConstants.setComponent(attr,lbl);
+        return attr;
+    }
+}