1 /*

     2  * Copyright (c) 2007, 2013, 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 com.sun.tools.classfile;

    27 

    28 import java.io.IOException;

    29 import java.util.Iterator;

    30 import java.util.NoSuchElementException;

    31 

    32 /**

    33  * See JVMS, section 4.8.3.

    34  *

    35  *  <p><b>This is NOT part of any supported API.

    36  *  If you write code that depends on this, you do so at your own risk.

    37  *  This code and its internal interfaces are subject to change or

    38  *  deletion without notice.</b>

    39  */

    40 public class Code_attribute extends Attribute {

    41     public static class InvalidIndex extends AttributeException {

    42         private static final long serialVersionUID = -8904527774589382802L;

    43         InvalidIndex(int index) {

    44             this.index = index;

    45         }

    46 

    47         @Override

    48         public String getMessage() {

    49             // i18n

    50             return "invalid index " + index + " in Code attribute";

    51         }

    52 

    53         public final int index;

    54     }

    55 

    56     Code_attribute(ClassReader cr, int name_index, int length)

    57             throws IOException, ConstantPoolException {

    58         super(name_index, length);

    59         max_stack = cr.readUnsignedShort();

    60         max_locals = cr.readUnsignedShort();

    61         code_length = cr.readInt();

    62         code = new byte[code_length];

    63         cr.readFully(code);

    64         exception_table_length = cr.readUnsignedShort();

    65         exception_table = new Exception_data[exception_table_length];

    66         for (int i = 0; i < exception_table_length; i++)

    67             exception_table[i] = new Exception_data(cr);

    68         attributes = new Attributes(cr);

    69     }

    70 

    71     public int getByte(int offset) throws InvalidIndex {

    72         if (offset < 0 || offset >= code.length)

    73             throw new InvalidIndex(offset);

    74         return code[offset];

    75     }

    76 

    77     public int getUnsignedByte(int offset) throws InvalidIndex {

    78         if (offset < 0 || offset >= code.length)

    79             throw new InvalidIndex(offset);

    80         return code[offset] & 0xff;

    81     }

    82 

    83     public int getShort(int offset) throws InvalidIndex {

    84         if (offset < 0 || offset + 1 >= code.length)

    85             throw new InvalidIndex(offset);

    86         return (code[offset] << 8) | (code[offset + 1] & 0xFF);

    87     }

    88 

    89     public int getUnsignedShort(int offset) throws InvalidIndex {

    90         if (offset < 0 || offset + 1 >= code.length)

    91             throw new InvalidIndex(offset);

    92         return ((code[offset] << 8) | (code[offset + 1] & 0xFF)) & 0xFFFF;

    93     }

    94 

    95     public int getInt(int offset) throws InvalidIndex {

    96         if (offset < 0 || offset + 3 >= code.length)

    97             throw new InvalidIndex(offset);

    98         return (getShort(offset) << 16) | (getShort(offset + 2) & 0xFFFF);

    99     }

   100 

   101     public <R, D> R accept(Visitor<R, D> visitor, D data) {

   102         return visitor.visitCode(this, data);

   103     }

   104 

   105     public Iterable<Instruction> getInstructions() {

   106         return new Iterable<Instruction>() {

   107             public Iterator<Instruction> iterator() {

   108                 return new Iterator<Instruction>() {

   109 

   110                     public boolean hasNext() {

   111                         return (next != null);

   112                     }

   113 

   114                     public Instruction next() {

   115                         if (next == null)

   116                             throw new NoSuchElementException();

   117 

   118                         current = next;

   119                         pc += current.length();

   120                         next = (pc < code.length ? new Instruction(code, pc) : null);

   121                         return current;

   122                     }

   123 

   124                     public void remove() {

   125                         throw new UnsupportedOperationException("Not supported.");

   126                     }

   127 

   128                     Instruction current = null;

   129                     int pc = 0;

   130                     Instruction next = new Instruction(code, pc);

   131 

   132                 };

   133             }

   134 

   135         };

   136     }

   137 

   138     public final int max_stack;

   139     public final int max_locals;

   140     public final int code_length;

   141     public final byte[] code;

   142     public final int exception_table_length;

   143     public final Exception_data[] exception_table;

   144     public final Attributes attributes;

   145 

   146     public static class Exception_data {

   147         Exception_data(ClassReader cr) throws IOException {

   148             start_pc = cr.readUnsignedShort();

   149             end_pc = cr.readUnsignedShort();

   150             handler_pc = cr.readUnsignedShort();

   151             catch_type = cr.readUnsignedShort();

   152         }

   153 

   154         public final int start_pc;

   155         public final int end_pc;

   156         public final int handler_pc;

   157         public final int catch_type;

   158     }

   159 }