Merge branch 'pr/4032'

docs/pages/release_notes.md

@@ -41,6 +41,8 @@ Being based on a proper Antlr grammar, CPD can:
 * honor [comment-based suppressions](pmd_userdocs_cpd.html#suppression)
 
 ### Fixed Issues
+* core
+    * [#4031](https://github.com/pmd/pmd/issues/4031): \[core] If report is written to stdout, stdout should not be closed
 * java
     * [#4015](https://github.com/pmd/pmd/issues/4015): \[java] Support JDK 19
 * java-bestpractices

pmd-core/src/main/java/net/sourceforge/pmd/cpd/CPD.java

@@ -4,11 +4,10 @@
 
 package net.sourceforge.pmd.cpd;
 
-import java.io.BufferedWriter;
 import java.io.File;
 import java.io.FileNotFoundException;
 import java.io.IOException;
-import java.io.OutputStreamWriter;
+import java.nio.charset.Charset;
 import java.util.ArrayList;
 import java.util.HashSet;
 import java.util.Iterator;
@@ -211,7 +210,7 @@ public class CPD {
                 // legacy writer
                 System.out.println(arguments.getRenderer().render(cpd.getMatches()));
             } else {
-                arguments.getCPDRenderer().render(cpd.getMatches(), new BufferedWriter(new OutputStreamWriter(System.out)));
+                arguments.getCPDRenderer().render(cpd.getMatches(), IOUtil.createWriter(Charset.defaultCharset(), null));
             }
             if (cpd.getMatches().hasNext()) {
                 if (arguments.isFailOnViolation()) {

pmd-core/src/main/java/net/sourceforge/pmd/util/IOUtil.java

@@ -8,6 +8,7 @@ import java.io.BufferedReader;
 import java.io.Closeable;
 import java.io.File;
 import java.io.FilterInputStream;
+import java.io.FilterOutputStream;
 import java.io.IOException;
 import java.io.InputStream;
 import java.io.OutputStream;
@@ -49,8 +50,16 @@ public final class IOUtil {
     private IOUtil() {
     }
 
+    /**
+     * Creates a writer that writes to stdout using the system default charset.
+     *
+     * @return a writer, never null
+     *
+     * @see #createWriter(String)
+     * @see #createWriter(Charset, String)
+     */
     public static Writer createWriter() {
-        return new OutputStreamWriter(System.out);
+        return createWriter(null);
     }
 
     /**
@@ -103,7 +112,12 @@ public final class IOUtil {
     public static Writer createWriter(Charset charset, String reportFile) {
         try {
             if (StringUtils.isBlank(reportFile)) {
-                return new OutputStreamWriter(System.out, charset);
+                return new OutputStreamWriter(new FilterOutputStream(System.out) {
+                    @Override
+                    public void close() {
+                        // do nothing, avoid closing stdout
+                    }
+                }, charset);
             }
             Path path = new File(reportFile).toPath().toAbsolutePath();
             Files.createDirectories(path.getParent()); // ensure parent dir exists

pmd-core/src/test/java/net/sourceforge/pmd/cli/CoreCliTest.java

@@ -12,8 +12,11 @@ import static org.junit.Assert.assertEquals;
 import static org.junit.Assert.assertFalse;
 import static org.junit.Assert.assertNotEquals;
 import static org.junit.Assert.assertTrue;
+import static org.junit.Assert.fail;
 
+import java.io.FilterOutputStream;
 import java.io.IOException;
+import java.io.PrintStream;
 import java.nio.ByteBuffer;
 import java.nio.charset.StandardCharsets;
 import java.nio.file.FileSystems;
@@ -190,6 +193,24 @@ public class CoreCliTest {
         }
     }
 
+    @Test
+    public void testReportToStdoutNotClosing() {
+        PrintStream originalOut = System.out;
+        PrintStream out = new PrintStream(new FilterOutputStream(originalOut) {
+            @Override
+            public void close() {
+                fail("Stream must not be closed");
+            }
+        });
+        try {
+            System.setOut(out);
+            startCapturingErrAndOut();
+            runPmd(StatusCode.VIOLATIONS_FOUND, "--no-cache", "--dir", srcDir, "--rulesets", "dummy-basic");
+        } finally {
+            System.setOut(originalOut);
+        }
+    }
+
     @Test
     public void testDeprecatedRulesetSyntaxOnCommandLine() {
         startCapturingErrAndOut();

pmd-core/src/test/java/net/sourceforge/pmd/util/IOUtilTest.java

@@ -4,15 +4,21 @@
 
 package net.sourceforge.pmd.util;
 
+import static org.junit.Assert.assertEquals;
+import static org.junit.Assert.fail;
+
 import java.io.ByteArrayInputStream;
 import java.io.ByteArrayOutputStream;
 import java.io.CharArrayReader;
+import java.io.FilterOutputStream;
 import java.io.IOException;
 import java.io.InputStream;
 import java.io.OutputStream;
+import java.io.PrintStream;
 import java.io.Reader;
 import java.io.StringReader;
 import java.io.StringWriter;
+import java.io.Writer;
 import java.nio.charset.Charset;
 import java.nio.charset.StandardCharsets;
 import java.nio.file.Files;
@@ -296,4 +302,26 @@ public class IOUtilTest {
         InputStream stream = new ByteArrayInputStream(testString.getBytes(StandardCharsets.UTF_8));
         Assert.assertEquals(testString, IOUtil.readToString(stream, StandardCharsets.UTF_8));
     }
+
+    @Test
+    public void testCreateWriterStdout() throws IOException {
+        PrintStream originalOut = System.out;
+        ByteArrayOutputStream data = new ByteArrayOutputStream();
+        PrintStream out = new PrintStream(new FilterOutputStream(data) {
+            @Override
+            public void close() {
+                fail("Stream must not be closed");
+            }
+        });
+
+        try {
+            System.setOut(out);
+            Writer writer = IOUtil.createWriter();
+            writer.write("Test");
+            writer.close();
+            assertEquals("Test", data.toString());
+        } finally {
+            System.setOut(originalOut);
+        }
+    }
 }