gt:             n = super.read(b, off, len);
context: /*
   * Copyright (c) 1997, 2021, 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.  Oracle designates this
   * particular file as subject to the "Classpath" exception as provided
   * by Oracle in the LICENSE file that accompanied this code.
   *
   * 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.
   */
  
  package java.util.jar;
  
  import java.util.zip.*;
  import java.io.*;
  import sun.security.util.ManifestEntryVerifier;
  import sun.misc.JarIndex;
  
  /**
   * The <code>JarInputStream</code> class is used to read the contents of
   * a JAR file from any input stream. It extends the class
   * <code>java.util.zip.ZipInputStream</code> with support for reading
   * an optional <code>Manifest</code> entry. The <code>Manifest</code>
   * can be used to store meta-information about the JAR file and its entries.
   *
   * @author  David Connelly
   * @see     Manifest
   * @see     java.util.zip.ZipInputStream
   * @since   1.2
   */
  public
  class JarInputStream extends ZipInputStream {
      private Manifest man;
      private JarEntry first;
      private JarVerifier jv;
      private ManifestEntryVerifier mev;
      private final boolean doVerify;
      private boolean tryManifest;
  
      /**
       * Creates a new <code>JarInputStream</code> and reads the optional
       * manifest. If a manifest is present, also attempts to verify
       * the signatures if the JarInputStream is signed.
       * @param in the actual input stream
       * @exception IOException if an I/O error has occurred
       */
      public JarInputStream(InputStream in) throws IOException {
          this(in, true);
      }
  
      /**
       * Creates a new <code>JarInputStream</code> and reads the optional
       * manifest. If a manifest is present and verify is true, also attempts
       * to verify the signatures if the JarInputStream is signed.
       *
       * @param in the actual input stream
       * @param verify whether or not to verify the JarInputStream if
       * it is signed.
       * @exception IOException if an I/O error has occurred
       */
      public JarInputStream(InputStream in, boolean verify) throws IOException {
          super(in);
          this.doVerify = verify;
  
          // This implementation assumes the META-INF/MANIFEST.MF entry
          // should be either the first or the second entry (when preceded
          // by the dir META-INF/). It skips the META-INF/ and then
          // "consumes" the MANIFEST.MF to initialize the Manifest object.
          JarEntry e = (JarEntry)super.getNextEntry();
          if (e != null && e.getName().equalsIgnoreCase("META-INF/"))
              e = (JarEntry)super.getNextEntry();
          first = checkManifest(e);
      }
  
      private JarEntry checkManifest(JarEntry e)
          throws IOException
      {
          if (e != null && JarFile.MANIFEST_NAME.equalsIgnoreCase(e.getName())) {
              man = new Manifest();
              byte bytes[] = getBytes(new BufferedInputStream(this));
              man.read(new ByteArrayInputStream(bytes));
              closeEntry();
              if (doVerify) {
                  jv = new JarVerifier(e.getName(), bytes);
                  mev = new ManifestEntryVerifier(man, jv.manifestName);
              }
              return (JarEntry)super.getNextEntry();
          }
          return e;
      }
  
      private byte[] getBytes(InputStream is)
          throws IOException
      {
          byte[] buffer = new byte[8192];
          ByteArrayOutputStream baos = new ByteArrayOutputStream(2048);
          int n;
          while ((n = is.read(buffer, 0, buffer.length)) != -1) {
              baos.write(buffer, 0, n);
          }
          return baos.toByteArray();
      }
  
      /**
       * Returns the <code>Manifest</code> for this JAR file, or
       * <code>null</code> if none.
       *
       * @return the <code>Manifest</code> for this JAR file, or
       *         <code>null</code> if none.
       */
      public Manifest getManifest() {
          return man;
      }
  
      /**
       * Reads the next ZIP file entry and positions the stream at the
       * beginning of the entry data. If verification has been enabled,
       * any invalid signature detected while positioning the stream for
       * the next entry will result in an exception.
       * @exception ZipException if a ZIP file error has occurred
       * @exception IOException if an I/O error has occurred
       * @exception SecurityException if any of the jar file entries
       *         are incorrectly signed.
       */
      public ZipEntry getNextEntry() throws IOException {
          JarEntry e;
          if (first == null) {
              e = (JarEntry)super.getNextEntry();
              if (tryManifest) {
                  e = checkManifest(e);
                  tryManifest = false;
              }
          } else {
              e = first;
              if (first.getName().equalsIgnoreCase(JarIndex.INDEX_NAME))
                  tryManifest = true;
              first = null;
          }
          if (jv != null && e != null) {
              // At this point, we might have parsed all the meta-inf
              // entries and have nothing to verify. If we have
              // nothing to verify, get rid of the JarVerifier object.
              if (jv.nothingToVerify() == true) {
                  jv = null;
                  mev = null;
              } else {
                  jv.beginEntry(e, mev);
              }
          }
          return e;
      }
  
      /**
       * Reads the next JAR file entry and positions the stream at the
       * beginning of the entry data. If verification has been enabled,
       * any invalid signature detected while positioning the stream for
       * the next entry will result in an exception.
       * @return the next JAR file entry, or null if there are no more entries
       * @exception ZipException if a ZIP file error has occurred
       * @exception IOException if an I/O error has occurred
       * @exception SecurityException if any of the jar file entries
       *         are incorrectly signed.
       */
      public JarEntry getNextJarEntry() throws IOException {
          return (JarEntry)getNextEntry();
      }
  
      /**
       * Reads from the current JAR file entry into an array of bytes.
       * If <code>len</code> is not zero, the method
       * blocks until some input is available; otherwise, no
       * bytes are read and <code>0</code> is returned.
       * If verification has been enabled, any invalid signature
       * on the current entry will be reported at some point before the
       * end of the entry is reached.
       * @param b the buffer into which the data is read
       * @param off the start offset in the destination array <code>b</code>
       * @param len the maximum number of bytes to read
       * @return the actual number of bytes read, or -1 if the end of the
       *         entry is reached
       * @exception  NullPointerException If <code>b</code> is <code>null</code>.
       * @exception  IndexOutOfBoundsException If <code>off</code> is negative,
       * <code>len</code> is negative, or <code>len</code> is greater than
       * <code>b.length - off</code>
       * @exception ZipException if a ZIP file error has occurred
       * @exception IOException if an I/O error has occurred
       * @exception SecurityException if any of the jar file entries
       *         are incorrectly signed.
       */
      public int read(byte[] b, int off, int len) throws IOException {
          int n;
          if (first == null) {
  