undefect. CWE-407 — 63 sites patched across 27 ecosystems

Authors: russell@unturf.com · brackishbert@gmail.com · foxhop.net · TimeHexOn.com

Patches, unit tests, benchmarks, whitepaper, and outreach briefs.
Public domain — no copyright claimed. Use freely.

test/jdk/java/io/Writer/NullWriter.java

@@ -0,0 +1,166 @@
+/*
+ * Copyright (c) 2018, 2026, 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.io.IOException;
+import java.io.Writer;
+
+import org.junit.jupiter.api.AfterAll;
+import org.junit.jupiter.api.BeforeAll;
+import org.junit.jupiter.api.Test;
+
+import static org.junit.jupiter.api.Assertions.assertNotNull;
+import static org.junit.jupiter.api.Assertions.assertSame;
+import static org.junit.jupiter.api.Assertions.assertThrows;
+
+/*
+ * @test
+ * @bug 8196298
+ * @run junit NullWriter
+ * @summary Check for expected behavior of Writer.nullWriter().
+ */
+public class NullWriter {
+    private static Writer openWriter;
+    private static Writer closedWriter;
+
+    @BeforeAll
+    public static void setup() throws IOException {
+        openWriter = Writer.nullWriter();
+        closedWriter = Writer.nullWriter();
+        closedWriter.close();
+    }
+
+    @AfterAll
+    public static void closeStream() throws IOException {
+        openWriter.close();
+    }
+
+    @Test
+    public void testOpen() {
+        assertNotNull(openWriter, "Writer.nullWriter() returned null");
+    }
+
+    @Test
+    public void testAppendChar() throws IOException {
+        assertSame(openWriter, openWriter.append('x'));
+    }
+
+    @Test
+    public void testAppendCharSequence() throws IOException {
+        CharSequence cs = "abc";
+        assertSame(openWriter, openWriter.append(cs));
+    }
+
+    @Test
+    public void testAppendCharSequenceNull() throws IOException {
+        assertSame(openWriter, openWriter.append(null));
+    }
+
+    @Test
+    public void testAppendCharSequenceII() throws IOException {
+        CharSequence cs = "abc";
+        assertSame(openWriter, openWriter.append(cs, 0, 1));
+    }
+
+    @Test
+    public void testAppendCharSequenceIINull() throws IOException {
+        assertSame(openWriter, openWriter.append(null, 2, 1));
+    }
+
+    @Test
+    public void testFlush() throws IOException {
+        openWriter.flush();
+    }
+
+    @Test
+    public void testWrite() throws IOException {
+        openWriter.write(62832);
+    }
+
+    @Test
+    public void testWriteString() throws IOException {
+        openWriter.write("");
+    }
+
+    @Test
+    public void testWriteStringII() throws IOException {
+        openWriter.write("", 0, 0);
+    }
+
+    @Test
+    public void testWriteBII() throws IOException, Exception {
+        openWriter.write(new char[]{(char) 6}, 0, 1);
+    }
+
+    @Test
+    public void testAppendCharClosed() throws IOException {
+        assertThrows(IOException.class, () -> closedWriter.append('x'));
+    }
+
+    @Test
+    public void testAppendCharSequenceClosed() throws IOException {
+        CharSequence cs = "abc";
+        assertThrows(IOException.class, () -> closedWriter.append(cs));
+    }
+
+    @Test
+    public void testAppendCharSequenceNullClosed() throws IOException {
+        assertThrows(IOException.class, () -> closedWriter.append(null));
+    }
+
+    @Test
+    public void testAppendCharSequenceIIClosed() throws IOException {
+        CharSequence cs = "abc";
+        assertThrows(IOException.class, () -> closedWriter.append(cs, 0, 1));
+    }
+
+    @Test
+    public void testAppendCharSequenceIINullClosed() throws IOException {
+        assertThrows(IOException.class, () -> closedWriter.append(null, 2, 1));
+    }
+
+    @Test
+    public void testFlushClosed() throws IOException {
+        assertThrows(IOException.class, () -> closedWriter.flush());
+    }
+
+    @Test
+    public void testWriteClosed() throws IOException {
+        assertThrows(IOException.class, () -> closedWriter.write(62832));
+    }
+
+    @Test
+    public void testWriteStringClosed() throws IOException {
+        assertThrows(IOException.class, () -> closedWriter.write(""));
+    }
+
+    @Test
+    public void testWriteStringIIClosed() throws IOException {
+        assertThrows(IOException.class, () -> closedWriter.write("", 0, 0));
+    }
+
+    @Test
+    public void testWriteBIIClosed() throws IOException {
+        assertThrows(IOException.class,
+                     () -> closedWriter.write(new char[]{(char) 6}, 0, 1));
+    }
+}