1 /*

     2  * Copyright (c) 2019, 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.tools.jlink.internal.plugins;

    27 

    28 import java.io.*;

    29 import java.nio.charset.*;

    30 import java.util.*;

    31 import java.util.function.*;

    32 import java.util.stream.*;

    33 import jdk.tools.jlink.plugin.*;

    34 import jdk.internal.org.objectweb.asm.*;

    35 

    36 import static java.lang.System.out;

    37 

    38 /**

    39  * Base plugin to update a static field in java.lang.VersionProps

    40  */

    41 abstract class VersionPropsPlugin implements Plugin {

    42 

    43     private static final String VERSION_PROPS_CLASS

    44         = "/java.base/java/lang/VersionProps.class";

    45 

    46     private final String name;

    47     private final String field;

    48     private String value;

    49 

    50     /**

    51      * @param field The name of the java.lang.VersionProps field to be redefined

    52      * @param option The option name

    53      */

    54     protected VersionPropsPlugin(String field, String option) {

    55         this.field = field;

    56         this.name = option;

    57     }

    58 

    59     /**

    60      * Shorthand constructor for when the option name can be derived from the

    61      * name of the field.

    62      *

    63      * @param field The name of the java.lang.VersionProps field to be redefined

    64      */

    65     protected VersionPropsPlugin(String field) {

    66         this(field, field.toLowerCase().replace('_', '-'));

    67     }

    68 

    69     @Override

    70     public String getName() {

    71         return name;

    72     }

    73 

    74     @Override

    75     public String getDescription() {

    76         return PluginsResourceBundle.getDescription(name);

    77     }

    78 

    79     @Override

    80     public Category getType() {

    81         return Category.TRANSFORMER;

    82     }

    83 

    84     @Override

    85     public boolean hasArguments() {

    86         return true;

    87     }

    88 

    89     @Override

    90     public boolean hasRawArgument() {

    91         return true;

    92     }

    93 

    94     @Override

    95     public String getArgumentsDescription() {

    96        return PluginsResourceBundle.getArgument(name);

    97     }

    98 

    99     @Override

   100     public void configure(Map<String, String> config) {

   101         var v = config.get(name);

   102         if (v == null)

   103             throw new AssertionError();

   104         value = v;

   105     }

   106 

   107     private boolean redefined = false;

   108 

   109     private byte[] redefine(byte[] classFile) {

   110 

   111         var cr = new ClassReader(classFile);

   112         var cw = new ClassWriter(0);

   113 

   114         cr.accept(new ClassVisitor(Opcodes.ASM7, cw) {

   115 

   116                 public MethodVisitor visitMethod(int access,

   117                                                  String name,

   118                                                  String desc,

   119                                                  String sig,

   120                                                  String[] xs)

   121                 {

   122                     if (name.equals("<clinit>"))

   123                         return new MethodVisitor(Opcodes.ASM7,

   124                                                  super.visitMethod(access,

   125                                                                    name,

   126                                                                    desc,

   127                                                                    sig,

   128                                                                    xs))

   129                             {

   130 

   131                                 public void visitFieldInsn(int opcode,

   132                                                            String owner,

   133                                                            String name,

   134                                                            String desc)

   135                                 {

   136                                     if (opcode == Opcodes.PUTSTATIC

   137                                         && name.equals(field))

   138                                     {

   139                                         // Discard the original value

   140                                         super.visitInsn(Opcodes.POP);

   141                                         // Load the value that we want

   142                                         super.visitLdcInsn(value);

   143                                         redefined = true;

   144                                     }

   145                                     super.visitFieldInsn(opcode, owner,

   146                                                          name, desc);

   147                                 }

   148 

   149                         };

   150                     else

   151                         return super.visitMethod(access, name, desc, sig, xs);

   152                 }

   153 

   154             }, 0);

   155 

   156         return cw.toByteArray();

   157 

   158     }

   159 

   160     @Override

   161     public ResourcePool transform(ResourcePool in, ResourcePoolBuilder out) {

   162         in.transformAndCopy(res -> {

   163                 if (res.type().equals(ResourcePoolEntry.Type.CLASS_OR_RESOURCE)) {

   164                     if (res.path().equals(VERSION_PROPS_CLASS)) {

   165                         return res.copyWithContent(redefine(res.contentBytes()));

   166                     }

   167                 }

   168                 return res;

   169             }, out);

   170         if (!redefined)

   171             throw new AssertionError(field);

   172         return out.build();

   173     }

   174 

   175 }