1 /* 2 * Copyright (C) 2009 The Android Open Source Project 3 * 4 * Licensed under the Apache License, Version 2.0 (the "License"); 5 * you may not use this file except in compliance with the License. 6 * You may obtain a copy of the License at 7 * 8 * http://www.apache.org/licenses/LICENSE-2.0 9 * 10 * Unless required by applicable law or agreed to in writing, software 11 * distributed under the License is distributed on an "AS IS" BASIS, 12 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. 13 * See the License for the specific language governing permissions and 14 * limitations under the License. 15 */ 16 17 package dex.reader; 18 19 import java.io.BufferedInputStream; 20 import java.io.ByteArrayOutputStream; 21 import java.io.FileInputStream; 22 import java.io.IOException; 23 import java.nio.ByteBuffer; 24 import java.nio.ByteOrder; 25 26 public final class DexBuffer { 27 28 private ByteBuffer b; 29 DexBuffer(String fileName)30 public DexBuffer(String fileName) throws IOException { 31 32 // FIXME channel? allocate fix size? 33 FileInputStream fis = null; 34 try { 35 fis = new FileInputStream(fileName); 36 37 BufferedInputStream bis = new BufferedInputStream(fis); 38 ByteArrayOutputStream bos = new ByteArrayOutputStream(); 39 byte[] buf = new byte[1024]; 40 int len; 41 while ((len = bis.read(buf)) > 0) { 42 bos.write(buf, 0, len); 43 } 44 byte[] bytes = bos.toByteArray(); 45 initialize(ByteBuffer.wrap(bytes)); 46 } finally { 47 if (fis != null) { 48 fis.close(); 49 } 50 } 51 } 52 DexBuffer(byte[] bytes)53 public DexBuffer(byte[] bytes) { 54 initialize(ByteBuffer.wrap(bytes)); 55 } 56 DexBuffer(ByteBuffer slice)57 private DexBuffer(ByteBuffer slice) { 58 initialize(slice); 59 } 60 initialize(ByteBuffer buffer)61 private void initialize(ByteBuffer buffer) { 62 b = buffer.asReadOnlyBuffer(); 63 b.clear(); 64 b.order(ByteOrder.LITTLE_ENDIAN); 65 } 66 setPosition(int offset)67 public void setPosition(int offset) { 68 b.position(offset); 69 } 70 readBytes(byte[] dst)71 public void readBytes(byte[] dst) { 72 b.get(dst, 0, dst.length); 73 } 74 75 /** 76 * FIXME make endian dependent 77 */ readUleb128()78 public int readUleb128() { 79 int endValue = 0; 80 int value = 0; 81 int nr = 0; 82 do { 83 value = (b.get() & 0xFF); 84 endValue |= ((value & 0x7F) << 7 * nr);// cut away left most bit 85 nr++; 86 } while ((value & 0x80) != 0); // highest bit set? 87 return endValue; 88 } 89 90 /** 91 * pre 0 < nBytes <=4 92 */ readInt(int nBytes)93 public int readInt(int nBytes) { 94 int endValue = 0; 95 int tmp = 0; 96 for (int i = 0; i < nBytes; i++) { 97 tmp = b.get() & 0xFF; 98 endValue |= (tmp << i * 8); 99 } 100 return endValue; 101 } 102 103 /** 104 * pre 0 < nBytes <=1 FIXME: Sign extension 105 */ readShort(int nBytes)106 public short readShort(int nBytes) { 107 short endValue = 0; 108 int tmp = 0; 109 for (int i = 0; i < nBytes; i++) { 110 tmp = b.get() & 0xFF; 111 endValue |= (tmp << i * 8); 112 } 113 return endValue; 114 } 115 116 /** 117 * pre 0 < nBytes <=1 118 */ readChar(int nBytes)119 public char readChar(int nBytes) { 120 char endValue = 0; 121 int tmp = 0; 122 for (int i = 0; i < nBytes; i++) { 123 tmp = b.get() & 0xFF; 124 endValue |= (tmp << i * 8); 125 } 126 return endValue; 127 } 128 129 /** 130 * pre 0 < nBytes <=7 FIXME: Sign extension 131 */ readLong(int nBytes)132 public long readLong(int nBytes) { 133 long endValue = 0; 134 int tmp = 0; 135 for (int i = 0; i < nBytes; i++) { 136 tmp = b.get() & 0xFF; 137 endValue |= (tmp << i * 8); 138 } 139 return endValue; 140 } 141 142 /** 143 * pre 0 < nBytes <=4 144 */ readFloat(int nBytes)145 public float readFloat(int nBytes) { 146 int bits = readInt(nBytes); 147 int bytesToMove = (4 - nBytes) * 8; 148 bits <<= bytesToMove; 149 return Float.intBitsToFloat(bits); 150 } 151 152 // returns int form current position readUInt()153 public int readUInt() { 154 int value = b.getInt(); 155 // assert value >= 0; 156 return value; 157 } 158 readUShort()159 public int readUShort() { 160 return b.getShort() & 0xFFFF; 161 } 162 163 // returns byte form current position readUByte()164 public byte readUByte() { 165 return b.get(); 166 } 167 createCopy()168 public DexBuffer createCopy() { 169 return new DexBuffer(b.duplicate()); 170 } 171 readDouble(int nBytes)172 public double readDouble(int nBytes) { 173 long bits = readLong(nBytes); 174 int bytesToMove = (8 - nBytes) * 8; 175 bits <<= bytesToMove; 176 return Double.longBitsToDouble(bits); 177 } 178 skip(int nBytes)179 public void skip(int nBytes) { 180 b.position(b.position() + nBytes); 181 } 182 } 183