1 /*

     2  * Copyright (c) 2016, 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 jdk.internal.util.jar;

    27 

    28 import java.util.Objects;

    29 import java.util.jar.JarEntry;

    30 import java.util.jar.JarFile;

    31 import java.util.stream.Stream;

    32 

    33 public class VersionedStream {

    34     private static final String META_INF_VERSIONS = "META-INF/versions/";

    35 

    36     /**

    37      * Returns a stream of versioned entries, derived from the base names of

    38      * all entries in a multi-release {@code JarFile} that are present either in

    39      * the base directory or in any versioned directory with a version number

    40      * less than or equal to the {@code Runtime.Version::major} that the

    41      * {@code JarFile} was opened with.  These versioned entries are aliases

    42      * for the real entries -- i.e. the names are base names and the content

    43      * may come from a versioned directory entry.  If the {@code jarFile} is not

    44      * a multi-release jar, a stream of all entries is returned.

    45      *

    46      * @param jf the input JarFile

    47      * @return stream of entries

    48      * @since 9

    49      */

    50     public static Stream<JarEntry> stream(JarFile jf) {

    51         if (jf.isMultiRelease()) {

    52             int version = jf.getVersion().major();

    53             return jf.stream()

    54                     .map(je -> getBaseSuffix(je, version))

    55                     .filter(Objects::nonNull)

    56                     .distinct()

    57                     .map(jf::getJarEntry);

    58         }

    59         return jf.stream();

    60     }

    61 

    62     private static String getBaseSuffix(JarEntry je, int version) {

    63         String name = je.getName();

    64         if (name.startsWith(META_INF_VERSIONS)) {

    65             int len = META_INF_VERSIONS.length();

    66             int index = name.indexOf('/', len);

    67             if (index == -1 || index == (name.length() - 1)) {

    68                 // filter out META-INF/versions/* and META-INF/versions/*/

    69                 return null;

    70             }

    71             try {

    72                 if (Integer.parseInt(name, len, index, 10) > version) {

    73                     // not an integer

    74                     return null;

    75                 }

    76             } catch (NumberFormatException x) {

    77                 // silently remove malformed entries

    78                 return null;

    79             }

    80             // We know name looks like META-INF/versions/*/*

    81             return name.substring(index + 1);

    82         }

    83         return name;

    84     }

    85 }