8038491: Improve synchronization in ZipFile.read()

Reviewed-by: alanb, chegar

src/share/classes/java/util/zip/ZipFile.java

@@ -700,24 +700,26 @@ class ZipFile implements ZipConstants, Closeable {
         }
 
         public int read(byte b[], int off, int len) throws IOException {
-            if (rem == 0) {
-                return -1;
-            }
-            if (len <= 0) {
-                return 0;
-            }
-            if (len > rem) {
-                len = (int) rem;
-            }
             synchronized (ZipFile.this) {
-                ensureOpenOrZipException();
+                long rem = this.rem;
+                long pos = this.pos;
+                if (rem == 0) {
+                    return -1;
+                }
+                if (len <= 0) {
+                    return 0;
+                }
+                if (len > rem) {
+                    len = (int) rem;
+                }
 
+                ensureOpenOrZipException();
                 len = ZipFile.read(ZipFile.this.jzfile, jzentry, pos, b,
                                    off, len);
-            }
-            if (len > 0) {
-                pos += len;
-                rem -= len;
+                if (len > 0) {
+                    this.pos = (pos + len);
+                    this.rem = (rem - len);
+                }
             }
             if (rem == 0) {
                 close();

test/java/util/zip/ZipFile/MultiThreadedReadTest.java

+/*
+ * Copyright (c) 2014, 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.
+ */
+
+/* @test
+ * @bug 8038491
+ * @summary Crash in ZipFile.read() when ZipFileInputStream is shared between threads
+ * @library /lib/testlibrary
+ * @build jdk.testlibrary.FileUtils
+ * @run main MultiThreadedReadTest
+ */
+
+import java.io.File;
+import java.io.FileOutputStream;
+import java.io.InputStream;
+import java.nio.file.Paths;
+import java.util.Random;
+import java.util.zip.ZipEntry;
+import java.util.zip.ZipFile;
+import java.util.zip.ZipOutputStream;
+import jdk.testlibrary.FileUtils;
+
+public class MultiThreadedReadTest extends Thread {
+
+    private static final int NUM_THREADS = 10;
+    private static final String ZIPFILE_NAME = "large.zip";
+    private static final String ZIPENTRY_NAME = "random.txt";
+    private static InputStream is = null;
+
+    public static void main(String args[]) throws Exception {
+        createZipFile();
+        try (ZipFile zf = new ZipFile(new File(ZIPFILE_NAME))) {
+            is = zf.getInputStream(zf.getEntry(ZIPENTRY_NAME));
+            Thread[] threadArray = new Thread[NUM_THREADS];
+            for (int i = 0; i < threadArray.length; i++) {
+                threadArray[i] = new MultiThreadedReadTest();
+            }
+            for (int i = 0; i < threadArray.length; i++) {
+                threadArray[i].start();
+            }
+            for (int i = 0; i < threadArray.length; i++) {
+                threadArray[i].join();
+            }
+        } finally {
+            FileUtils.deleteFileIfExistsWithRetry(Paths.get(ZIPFILE_NAME));
+        }
+    }
+
+    private static void createZipFile() throws Exception {
+        try (ZipOutputStream zos =
+            new ZipOutputStream(new FileOutputStream(ZIPFILE_NAME))) {
+
+            zos.putNextEntry(new ZipEntry(ZIPENTRY_NAME));
+            StringBuilder sb = new StringBuilder();
+            Random rnd = new Random();
+            for(int i = 0; i < 1000; i++) {
+                // append some random string for ZipEntry
+                sb.append(Long.toString(rnd.nextLong()));
+            }
+            byte[] b = sb.toString().getBytes();
+            zos.write(b, 0, b.length);
+        }
+    }
+
+    @Override
+    public void run() {
+        try {
+            while (is.read() != -1) { }
+        } catch (Exception e) {
+            // Swallow any Exceptions (which are expected) - we're only interested in the crash
+        }
+    }
+}