8289643: File descriptor leak with ProcessBuilder.startPipeline

Reviewed-by: alanb, jpai, lancea

src/java.base/share/classes/java/lang/ProcessBuilder.java

@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 2003, 2021, Oracle and/or its affiliates. All rights reserved.
+ * Copyright (c) 2003, 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
@@ -1296,6 +1296,10 @@ public static List<Process> startPipeline(List<ProcessBuilder> builders) throws
                     redirects[1] = new RedirectPipeImpl();  // placeholder for new output
                 }
                 processes.add(builder.start(redirects));
+                if (prevOutput instanceof RedirectPipeImpl redir) {
+                    // Wrap the fd so it can be closed
+                    new Process.PipeInputStream(redir.getFd()).close();
+                }
                 prevOutput = redirects[1];
             }
         } catch (Exception ex) {

test/jdk/java/lang/ProcessBuilder/PipelineLeaksFD.java

@@ -0,0 +1,139 @@
+/*
+ * 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 org.testng.Assert;
+import org.testng.annotations.DataProvider;
+import org.testng.annotations.Test;
+
+import java.io.File;
+import java.io.IOException;
+import java.io.InputStream;
+import java.io.OutputStream;
+import java.nio.file.Files;
+import java.nio.file.Path;
+import java.util.HashSet;
+import java.util.List;
+import java.util.Set;
+
+/*
+ * @test
+ * @bug 8289643
+ * @requires (os.family == "linux" & !vm.musl)
+ * @summary file descriptor leak with ProcessBuilder.startPipeline
+ * @run testng/othervm PipelineLeaksFD
+ */
+
+@Test
+public class PipelineLeaksFD {
+    @DataProvider
+    public Object[][] builders() {
+        return new Object[][]{
+                {List.of(new ProcessBuilder("cat"))},
+                {List.of(new ProcessBuilder("cat"),
+                        new ProcessBuilder("cat"))},
+                {List.of(new ProcessBuilder("cat"),
+                        new ProcessBuilder("cat"),
+                        new ProcessBuilder("cat"),
+                        new ProcessBuilder("cat"),
+                        new ProcessBuilder("cat"))},
+        };
+    }
+
+    @Test(dataProvider = "builders")
+    void checkForLeaks(List<ProcessBuilder> builders) throws IOException {
+
+        Set<PipeRecord> pipesBefore = myPipes();
+        if (pipesBefore.size() < 3) {
+            System.out.println(pipesBefore);
+            Assert.fail("There should be at least 3 pipes before, (0, 1, 2)");
+        }
+
+        List<Process> processes = ProcessBuilder.startPipeline(builders);
+
+        OutputStream out = processes.get(0).getOutputStream();
+        out.write('a');
+        out.close();
+
+        Process last = processes.get(processes.size() - 1);
+        try (InputStream inputStream = last.getInputStream();
+             InputStream errorStream = last.getErrorStream()) {
+            byte[] bytes = inputStream.readAllBytes();
+            Assert.assertEquals(bytes.length, 1, "stdout bytes read");
+            byte[] errBytes = errorStream.readAllBytes();
+            Assert.assertEquals(errBytes.length, 0, "stderr bytes read");
+        }
+
+        processes.forEach(p -> waitForQuiet(p));
+
+        Set<PipeRecord> pipesAfter = myPipes();
+        printPipes(pipesAfter, "DEBUG: All Pipes After");
+        if (!pipesBefore.equals(pipesAfter)) {
+            Set<PipeRecord> missing = new HashSet<>(pipesBefore);
+            missing.removeAll(pipesAfter);
+            printPipes(missing, "Missing from pipesAfter");
+            Set<PipeRecord> extra = new HashSet<>(pipesAfter);
+            extra.removeAll(pipesBefore);
+            printPipes(extra, "Extra pipes in pipesAfter");
+            Assert.fail("More or fewer pipes than expected");
+        }
+    }
+
+    static void printPipes(Set<PipeRecord> pipes, String label) {
+        System.out.printf("%s: [%d]%n", label, pipes.size());
+        pipes.forEach(r -> System.out.printf("%-20s: %s%n", r.fd(), r.link()));
+    }
+
+    static void waitForQuiet(Process p) {
+        try {
+            int st = p.waitFor();
+            if (st != 0) {
+                System.out.println("non-zero exit status: " + p);
+            }
+        } catch (InterruptedException ie) {
+        }
+    }
+
+    /**
+     * Collect a Set of pairs of /proc fd paths and the symbol links that are pipes.
+     * @return A set of PipeRecords, possibly empty
+     */
+    static Set<PipeRecord> myPipes() {
+        Path path = Path.of("/proc/" + ProcessHandle.current().pid() + "/fd");
+        Set<PipeRecord> pipes = new HashSet<>();
+        File[] files = path.toFile().listFiles(f -> Files.isSymbolicLink(f.toPath()));
+        if (files != null) {
+            for (File file : files) {
+                try {
+                    Path link = Files.readSymbolicLink(file.toPath());
+                    if (link.toString().startsWith("pipe:")) {
+                        pipes.add(new PipeRecord(file.toPath(), link));
+                    }
+                } catch (IOException ioe) {
+                }
+            }
+        }
+        return pipes;
+    }
+
+    record PipeRecord(Path fd, Path link) { };
+}