1 /* 2 * Copyright (C) 2011 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 com.android.dex; 18 19 /** 20 * Constants that show up in and are otherwise related to {@code .dex} 21 * files, and helper methods for same. 22 */ 23 public final class DexFormat { DexFormat()24 private DexFormat() {} 25 26 /** API level to target in order to allow spaces in SimpleName */ 27 public static final int API_SPACES_IN_SIMPLE_NAME = 10000; 28 29 /** API level to target in order to generate const-method-handle and const-method-type */ 30 public static final int API_CONST_METHOD_HANDLE = 28; 31 32 /** API level to target in order to generate invoke-polymorphic and invoke-custom */ 33 public static final int API_METHOD_HANDLES = 26; 34 35 /** API level to target in order to define default and static interface methods */ 36 public static final int API_DEFINE_INTERFACE_METHODS = 24; 37 38 /** API level to target in order to invoke default and static interface methods */ 39 public static final int API_INVOKE_INTERFACE_METHODS = 24; 40 41 /** API level at which the invocation of static interface methods is permitted by dx. 42 * This value has been determined experimentally by testing on different VM versions. */ 43 public static final int API_INVOKE_STATIC_INTERFACE_METHODS = 21; 44 45 /** API level to target in order to suppress extended opcode usage */ 46 public static final int API_NO_EXTENDED_OPCODES = 13; 47 48 /** 49 * API level to target in order to produce the most modern file 50 * format 51 */ 52 public static final int API_CURRENT = API_CONST_METHOD_HANDLE; 53 54 /** dex file version number for API level 10000 and earlier */ 55 public static final String VERSION_FOR_API_10000 = "040"; 56 57 /** dex file version number for API level 28 and earlier */ 58 public static final String VERSION_FOR_API_28 = "039"; 59 60 /** dex file version number for API level 26 and earlier */ 61 public static final String VERSION_FOR_API_26 = "038"; 62 63 /** dex file version number for API level 24 and earlier */ 64 public static final String VERSION_FOR_API_24 = "037"; 65 66 /** dex file version number for API level 13 and earlier */ 67 public static final String VERSION_FOR_API_13 = "035"; 68 69 /** 70 * Dex file version number for dalvik. 71 * <p> 72 * Note: Dex version 36 was loadable in some versions of Dalvik but was never fully supported or 73 * completed and is not considered a valid dex file format. 74 * </p> 75 */ 76 public static final String VERSION_CURRENT = VERSION_FOR_API_28; 77 78 /** 79 * file name of the primary {@code .dex} file inside an 80 * application or library {@code .jar} file 81 */ 82 public static final String DEX_IN_JAR_NAME = "classes.dex"; 83 84 /** common prefix for all dex file "magic numbers" */ 85 public static final String MAGIC_PREFIX = "dex\n"; 86 87 /** common suffix for all dex file "magic numbers" */ 88 public static final String MAGIC_SUFFIX = "\0"; 89 90 /** 91 * value used to indicate endianness of file contents 92 */ 93 public static final int ENDIAN_TAG = 0x12345678; 94 95 /** 96 * Maximum addressable field or method index. 97 * The largest addressable member is 0xffff, in the "instruction formats" spec as field@CCCC or 98 * meth@CCCC. 99 */ 100 public static final int MAX_MEMBER_IDX = 0xFFFF; 101 102 /** 103 * Maximum addressable type index. 104 * The largest addressable type is 0xffff, in the "instruction formats" spec as type@CCCC. 105 */ 106 public static final int MAX_TYPE_IDX = 0xFFFF; 107 108 /** 109 * Returns the API level corresponding to the given magic number, 110 * or {@code -1} if the given array is not a well-formed dex file 111 * magic number. 112 * 113 * @param magic array of bytes containing DEX file magic string 114 * @return API level corresponding to magic string if valid, -1 otherwise. 115 */ magicToApi(byte[] magic)116 public static int magicToApi(byte[] magic) { 117 if (magic.length != 8) { 118 return -1; 119 } 120 121 if ((magic[0] != 'd') || (magic[1] != 'e') || (magic[2] != 'x') || (magic[3] != '\n') || 122 (magic[7] != '\0')) { 123 return -1; 124 } 125 126 String version = "" + ((char) magic[4]) + ((char) magic[5]) +((char) magic[6]); 127 128 if (version.equals(VERSION_FOR_API_13)) { 129 return API_NO_EXTENDED_OPCODES; 130 } else if (version.equals(VERSION_FOR_API_24)) { 131 return API_DEFINE_INTERFACE_METHODS; 132 } else if (version.equals(VERSION_FOR_API_26)) { 133 return API_METHOD_HANDLES; 134 } else if (version.equals(VERSION_FOR_API_28)) { 135 return API_CONST_METHOD_HANDLE; 136 } else if (version.equals(VERSION_FOR_API_10000)) { 137 return API_SPACES_IN_SIMPLE_NAME; 138 } else if (version.equals(VERSION_CURRENT)) { 139 return API_CURRENT; 140 } 141 142 return -1; 143 } 144 145 /** 146 * Returns the magic number corresponding to the given target API level. 147 * 148 * @param targetApiLevel level of API (minimum supported value 13). 149 * @return Magic string corresponding to API level supplied. 150 */ apiToMagic(int targetApiLevel)151 public static String apiToMagic(int targetApiLevel) { 152 String version; 153 154 if (targetApiLevel >= API_CURRENT) { 155 version = VERSION_CURRENT; 156 } else if (targetApiLevel >= API_SPACES_IN_SIMPLE_NAME) { 157 version = VERSION_FOR_API_10000; 158 } else if (targetApiLevel >= API_CONST_METHOD_HANDLE) { 159 version = VERSION_FOR_API_28; 160 } else if (targetApiLevel >= API_METHOD_HANDLES) { 161 version = VERSION_FOR_API_26; 162 } else if (targetApiLevel >= API_DEFINE_INTERFACE_METHODS) { 163 version = VERSION_FOR_API_24; 164 } else { 165 version = VERSION_FOR_API_13; 166 } 167 168 return MAGIC_PREFIX + version + MAGIC_SUFFIX; 169 } 170 171 /** 172 * Checks whether a DEX file magic string is supported. 173 * @param magic string from DEX file 174 * @return 175 */ isSupportedDexMagic(byte[] magic)176 public static boolean isSupportedDexMagic(byte[] magic) { 177 int api = magicToApi(magic); 178 return api > 0; 179 } 180 } 181