1 /*
   2  * Copyright (c) 2011, 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.oracle.ipack.macho;
  27 
  28 import java.io.DataInput;
  29 import java.io.DataOutput;
  30 import java.io.IOException;
  31 
  32 public abstract class MachoCommand {
  33     public static final int LC_SEGMENT = 0x1;
  34     public static final int LC_CODE_SIGNATURE = 0x1d;
  35 
  36     public abstract int getId();
  37 
  38     public final int getSize() {
  39         return 8 + getPayloadSize();
  40     }
  41 
  42     public static MachoCommand read(final DataInput dataInput)
  43             throws IOException {
  44         final int commandId = dataInput.readInt();
  45         final int commandSize = dataInput.readInt();
  46         MachoCommand command;
  47         switch (commandId) {
  48             case LC_SEGMENT:
  49                 command = new SegmentCommand();
  50                 break;
  51             case LC_CODE_SIGNATURE:
  52                 command = new CodeSignatureCommand();
  53                 break;
  54             default:
  55                 command = new UnknownCommand(commandId, commandSize - 8);
  56                 break;
  57         }
  58 
  59         command.readPayload(dataInput);
  60         if (command.getSize() != commandSize) {
  61             throw new IOException("Can't decode command in mach-o header");
  62         }
  63 
  64         return command;
  65     }
  66 
  67     public final void write(final DataOutput dataOutput) throws IOException {
  68         dataOutput.writeInt(getId());
  69         dataOutput.writeInt(getSize());
  70         writePayload(dataOutput);
  71     }
  72 
  73     protected abstract int getPayloadSize();
  74 
  75     protected abstract void readPayload(final DataInput dataInput)
  76             throws IOException;
  77 
  78     protected abstract void writePayload(final DataOutput dataOutput)
  79             throws IOException;
  80 }