content: /*
   * Copyright (c) 1997, 2012, 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.*;
  
  /**
   * The <code>JarOutputStream</code> class is used to write the contents
   * of a JAR file to any output stream. It extends the class
   * <code>java.util.zip.ZipOutputStream</code> with support
   * for writing an optional <code>Manifest</code> entry. The
   * <code>Manifest</code> can be used to specify meta-information about
   * the JAR file and its entries.
   *
   * @author  David Connelly
   * @see     Manifest
   * @see     ZipOutputStream
   * @since   1.2
   */
  public
  class JarOutputStream extends ZipOutputStream {
      private static final int JAR_MAGIC = 0xCAFE;
  
      /**
       * Creates a new <code>JarOutputStream</code> with the specified
       * <code>Manifest</code>. The manifest is written as the first
       * entry to the output stream.
       *
       * @param out the actual output stream
       * @param man the optional <code>Manifest</code>
       * @exception IOException if an I/O error has occurred
       */
      public JarOutputStream(OutputStream out, Manifest man) throws IOException {
          super(out);
          if (man == null) {
              throw new NullPointerException("man");
          }
          ZipEntry e = new ZipEntry(JarFile.MANIFEST_NAME);
          putNextEntry(e);
          man.write(new BufferedOutputStream(this));
          closeEntry();
      }
  
      /**
       * Creates a new <code>JarOutputStream</code> with no manifest.
       * @param out the actual output stream
       * @exception IOException if an I/O error has occurred
       */
      public JarOutputStream(OutputStream out) throws IOException {
          super(out);
      }
  
      /**
       * Begins writing a new JAR file entry and positions the stream
       * to the start of the entry data. This method will also close
       * any previous entry. The default compression method will be
       * used if no compression method was specified for the entry.
       * The current time will be used if the entry has no set modification
       * time.
       *
       * @param ze the ZIP/JAR entry to be written
       * @exception ZipException if a ZIP error has occurred
       * @exception IOException if an I/O error has occurred
       */
      public void putNextEntry(ZipEntry ze) throws IOException {
          if (firstEntry) {
              // Make sure that extra field data for first JAR
              // entry includes JAR magic number id.
              byte[] edata = ze.getExtra();
              if (edata == null || !hasMagic(edata)) {
                  if (edata == null) {
                      edata = new byte[4];
                  } else {
                      // Prepend magic to existing extra data
                      byte[] tmp = new byte[edata.length + 4];
                      System.arraycopy(edata, 0, tmp, 4, edata.length);
                      edata = tmp;
                  }
                  set16(edata, 0, JAR_MAGIC); // extra field id
                  set16(edata, 2, 0);         // extra field size
                  ze.setExtra(edata);
              }
              firstEntry = false;
          }
          super.putNextEntry(ze);
      }
  
      private boolean firstEntry = true;
  
      /*
       * Returns true if specified byte array contains the
       * jar magic extra field id.
       */
      private static boolean hasMagic(byte[] edata) {
          try {
              int i = 0;
              while (i < edata.length) {
                  if (get16(edata, i) == JAR_MAGIC) {
                      return true;
                  }
                  i += get16(edata, i + 2) + 4;
              }
          } catch (ArrayIndexOutOfBoundsException e) {
              // Invalid extra field data
          }
          return false;
      }
  
      /*
       * Fetches unsigned 16-bit value from byte array at specified offset.
       * The bytes are assumed to be in Intel (little-endian) byte order.
       */
      private static int get16(byte[] b, int off) {
          return Byte.toUnsignedInt(b[off]) | ( Byte.toUnsignedInt(b[off+1]) << 8);
      }
  
      /*
       * Sets 16-bit value at specified offset. The bytes are assumed to
       * be in Intel (little-endian) byte order.
       */
      private static void set16(byte[] b, int off, int value) {
          b[off+0] = (byte)value;
          b[off+1] = (byte)(value >> 8);
      }
  }
  