1 /*

     2  * Copyright (c) 1997, 2012, Oracle and/or its affiliates. All rights reserved.

     3  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.

     4  *

     5  * This code is free software; you can redistribute it and/or modify it

     6  * under the terms of the GNU General Public License version 2 only, as

     7  * published by the Free Software Foundation.  Oracle designates this

     8  * particular file as subject to the "Classpath" exception as provided

     9  * by Oracle in the LICENSE file that accompanied this code.

    10  *

    11  * This code is distributed in the hope that it will be useful, but WITHOUT

    12  * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or

    13  * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License

    14  * version 2 for more details (a copy is included in the LICENSE file that

    15  * accompanied this code).

    16  *

    17  * You should have received a copy of the GNU General Public License version

    18  * 2 along with this work; if not, write to the Free Software Foundation,

    19  * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.

    20  *

    21  * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA

    22  * or visit www.oracle.com if you need additional information or have any

    23  * questions.

    24  */

    25 

    26 package java.util.jar;

    27 

    28 import java.util.zip.*;

    29 import java.io.*;

    30 

    31 /**

    32  * The <code>JarOutputStream</code> class is used to write the contents

    33  * of a JAR file to any output stream. It extends the class

    34  * <code>java.util.zip.ZipOutputStream</code> with support

    35  * for writing an optional <code>Manifest</code> entry. The

    36  * <code>Manifest</code> can be used to specify meta-information about

    37  * the JAR file and its entries.

    38  *

    39  * @author  David Connelly

    40  * @see     Manifest

    41  * @see     java.util.zip.ZipOutputStream

    42  * @since   1.2

    43  */

    44 public

    45 class JarOutputStream extends ZipOutputStream {

    46     private static final int JAR_MAGIC = 0xCAFE;

    47 

    48     /**

    49      * Creates a new <code>JarOutputStream</code> with the specified

    50      * <code>Manifest</code>. The manifest is written as the first

    51      * entry to the output stream.

    52      *

    53      * @param out the actual output stream

    54      * @param man the optional <code>Manifest</code>

    55      * @exception IOException if an I/O error has occurred

    56      */

    57     public JarOutputStream(OutputStream out, Manifest man) throws IOException {

    58         super(out);

    59         if (man == null) {

    60             throw new NullPointerException("man");

    61         }

    62         ZipEntry e = new ZipEntry(JarFile.MANIFEST_NAME);

    63         putNextEntry(e);

    64         man.write(new BufferedOutputStream(this));

    65         closeEntry();

    66     }

    67 

    68     /**

    69      * Creates a new <code>JarOutputStream</code> with no manifest.

    70      * @param out the actual output stream

    71      * @exception IOException if an I/O error has occurred

    72      */

    73     public JarOutputStream(OutputStream out) throws IOException {

    74         super(out);

    75     }

    76 

    77     /**

    78      * Begins writing a new JAR file entry and positions the stream

    79      * to the start of the entry data. This method will also close

    80      * any previous entry. The default compression method will be

    81      * used if no compression method was specified for the entry.

    82      * The current time will be used if the entry has no set modification

    83      * time.

    84      *

    85      * @param ze the ZIP/JAR entry to be written

    86      * @exception ZipException if a ZIP error has occurred

    87      * @exception IOException if an I/O error has occurred

    88      */

    89     public void putNextEntry(ZipEntry ze) throws IOException {

    90         if (firstEntry) {

    91             // Make sure that extra field data for first JAR

    92             // entry includes JAR magic number id.

    93             byte[] edata = ze.getExtra();

    94             if (edata == null || !hasMagic(edata)) {

    95                 if (edata == null) {

    96                     edata = new byte[4];

    97                 } else {

    98                     // Prepend magic to existing extra data

    99                     byte[] tmp = new byte[edata.length + 4];

   100                     System.arraycopy(edata, 0, tmp, 4, edata.length);

   101                     edata = tmp;

   102                 }

   103                 set16(edata, 0, JAR_MAGIC); // extra field id

   104                 set16(edata, 2, 0);         // extra field size

   105                 ze.setExtra(edata);

   106             }

   107             firstEntry = false;

   108         }

   109         super.putNextEntry(ze);

   110     }

   111 

   112     private boolean firstEntry = true;

   113 

   114     /*

   115      * Returns true if specified byte array contains the

   116      * jar magic extra field id.

   117      */

   118     private static boolean hasMagic(byte[] edata) {

   119         try {

   120             int i = 0;

   121             while (i < edata.length) {

   122                 if (get16(edata, i) == JAR_MAGIC) {

   123                     return true;

   124                 }

   125                 i += get16(edata, i + 2) + 4;

   126             }

   127         } catch (ArrayIndexOutOfBoundsException e) {

   128             // Invalid extra field data

   129         }

   130         return false;

   131     }

   132 

   133     /*

   134      * Fetches unsigned 16-bit value from byte array at specified offset.

   135      * The bytes are assumed to be in Intel (little-endian) byte order.

   136      */

   137     private static int get16(byte[] b, int off) {

   138         return Byte.toUnsignedInt(b[off]) | ( Byte.toUnsignedInt(b[off+1]) << 8);

   139     }

   140 

   141     /*

   142      * Sets 16-bit value at specified offset. The bytes are assumed to

   143      * be in Intel (little-endian) byte order.

   144      */

   145     private static void set16(byte[] b, int off, int value) {

   146         b[off+0] = (byte)value;

   147         b[off+1] = (byte)(value >> 8);

   148     }

   149 }