org.snapscript.dx.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 org.snapscript.dx.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 produce the most modern file
* format
*/
public static final int API_CURRENT = 14;
/** API level to target in order to suppress extended opcode usage */
public static final int API_NO_EXTENDED_OPCODES = 13;
/**
* 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";
/** dex file version number for the current format variant */
public static final String VERSION_CURRENT = "036";
/** dex file version number for API level 13 and earlier */
public static final String VERSION_FOR_API_13 = "035";
/**
* value used to indicate endianness of file contents
*/
public static final int ENDIAN_TAG = 0x12345678;
/**
* 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.
*/
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_CURRENT)) {
return API_CURRENT;
} else if (version.equals(VERSION_FOR_API_13)) {
return 13;
}
return -1;
}
/**
* Returns the magic number corresponding to the given target API level.
*/
public static String apiToMagic(int targetApiLevel) {
String version;
if (targetApiLevel >= API_CURRENT) {
version = VERSION_CURRENT;
} else {
version = VERSION_FOR_API_13;
}
return MAGIC_PREFIX + version + MAGIC_SUFFIX;
}
}