com.android.dex.DexFormat Maven / Gradle / Ivy
/*
* Copyright (C) 2011 The Android Open Source Project
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
package com.android.dex;
/**
* Constants that show up in and are otherwise related to {@code .dex}
* files, and helper methods for same.
*/
public final class DexFormat {
private DexFormat() {}
/** API level to target in order to generate const-method-handle and const-method-type */
public static final int API_CONST_METHOD_HANDLE = 28;
/** API level to target in order to generate invoke-polymorphic and invoke-custom */
public static final int API_METHOD_HANDLES = 26;
/** API level to target in order to define default and static interface methods */
public static final int API_DEFINE_INTERFACE_METHODS = 24;
/** API level to target in order to invoke default and static interface methods */
public static final int API_INVOKE_INTERFACE_METHODS = 24;
/** API level at which the invocation of static interface methods is permitted by dx.
* This value has been determined experimentally by testing on different VM versions. */
public static final int API_INVOKE_STATIC_INTERFACE_METHODS = 21;
/** API level to target in order to suppress extended opcode usage */
public static final int API_NO_EXTENDED_OPCODES = 13;
/**
* API level to target in order to produce the most modern file
* format
*/
public static final int API_CURRENT = API_CONST_METHOD_HANDLE;
/** dex file version number for API level 28 and earlier */
public static final String VERSION_FOR_API_28 = "039";
/** dex file version number for API level 26 and earlier */
public static final String VERSION_FOR_API_26 = "038";
/** dex file version number for API level 24 and earlier */
public static final String VERSION_FOR_API_24 = "037";
/** dex file version number for API level 13 and earlier */
public static final String VERSION_FOR_API_13 = "035";
/**
* Dex file version number for dalvik.
*
* Note: Dex version 36 was loadable in some versions of Dalvik but was never fully supported or
* completed and is not considered a valid dex file format.
*
*/
public static final String VERSION_CURRENT = VERSION_FOR_API_28;
/**
* file name of the primary {@code .dex} file inside an
* application or library {@code .jar} file
*/
public static final String DEX_IN_JAR_NAME = "classes.dex";
/** common prefix for all dex file "magic numbers" */
public static final String MAGIC_PREFIX = "dex\n";
/** common suffix for all dex file "magic numbers" */
public static final String MAGIC_SUFFIX = "\0";
/**
* value used to indicate endianness of file contents
*/
public static final int ENDIAN_TAG = 0x12345678;
/**
* Maximum addressable field or method index.
* The largest addressable member is 0xffff, in the "instruction formats" spec as field@CCCC or
* meth@CCCC.
*/
public static final int MAX_MEMBER_IDX = 0xFFFF;
/**
* Maximum addressable type index.
* The largest addressable type is 0xffff, in the "instruction formats" spec as type@CCCC.
*/
public static final int MAX_TYPE_IDX = 0xFFFF;
/**
* Returns the API level corresponding to the given magic number,
* or {@code -1} if the given array is not a well-formed dex file
* magic number.
*
* @param magic array of bytes containing DEX file magic string
* @return API level corresponding to magic string if valid, -1 otherwise.
*/
public static int magicToApi(byte[] magic) {
if (magic.length != 8) {
return -1;
}
if ((magic[0] != 'd') || (magic[1] != 'e') || (magic[2] != 'x') || (magic[3] != '\n') ||
(magic[7] != '\0')) {
return -1;
}
String version = "" + ((char) magic[4]) + ((char) magic[5]) +((char) magic[6]);
if (version.equals(VERSION_FOR_API_13)) {
return API_NO_EXTENDED_OPCODES;
} else if (version.equals(VERSION_FOR_API_24)) {
return API_DEFINE_INTERFACE_METHODS;
} else if (version.equals(VERSION_FOR_API_26)) {
return API_METHOD_HANDLES;
} else if (version.equals(VERSION_FOR_API_28)) {
return API_CONST_METHOD_HANDLE;
} else if (version.equals(VERSION_CURRENT)) {
return API_CURRENT;
}
return -1;
}
/**
* Returns the magic number corresponding to the given target API level.
*
* @param targetApiLevel level of API (minimum supported value 13).
* @return Magic string corresponding to API level supplied.
*/
public static String apiToMagic(int targetApiLevel) {
String version;
if (targetApiLevel >= API_CURRENT) {
version = VERSION_CURRENT;
} else if (targetApiLevel >= API_CONST_METHOD_HANDLE) {
version = VERSION_FOR_API_28;
} else if (targetApiLevel >= API_METHOD_HANDLES) {
version = VERSION_FOR_API_26;
} else if (targetApiLevel >= API_DEFINE_INTERFACE_METHODS) {
version = VERSION_FOR_API_24;
} else {
version = VERSION_FOR_API_13;
}
return MAGIC_PREFIX + version + MAGIC_SUFFIX;
}
/**
* Checks whether a DEX file magic string is supported.
* @param magic string from DEX file
* @return
*/
public static boolean isSupportedDexMagic(byte[] magic) {
int api = magicToApi(magic);
return api > 0;
}
}