| /* |
| * Licensed to the Apache Software Foundation (ASF) under one or more |
| * contributor license agreements. See the NOTICE file distributed with |
| * this work for additional information regarding copyright ownership. |
| * The ASF licenses this file to You 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. |
| */ |
| /* Apache Harmony HEADER because the code in this class comes mostly from ZipFile, ZipEntry and |
| * ZipConstants from android libcore. |
| */ |
| |
| package android.support.multidex; |
| |
| import java.io.File; |
| import java.io.IOException; |
| import java.io.RandomAccessFile; |
| import java.util.zip.CRC32; |
| import java.util.zip.ZipException; |
| |
| /** |
| * Tools to build a quick partial crc of zip files. |
| */ |
| final class ZipUtil { |
| static class CentralDirectory { |
| long offset; |
| long size; |
| } |
| |
| /* redefine those constant here because of bug 13721174 preventing to compile using the |
| * constants defined in ZipFile */ |
| private static final int ENDHDR = 22; |
| private static final int ENDSIG = 0x6054b50; |
| |
| /** |
| * Size of reading buffers. |
| */ |
| private static final int BUFFER_SIZE = 0x4000; |
| |
| /** |
| * Compute crc32 of the central directory of an apk. The central directory contains |
| * the crc32 of each entries in the zip so the computed result is considered valid for the whole |
| * zip file. Does not support zip64 nor multidisk but it should be OK for now since ZipFile does |
| * not either. |
| */ |
| static long getZipCrc(File apk) throws IOException { |
| RandomAccessFile raf = new RandomAccessFile(apk, "r"); |
| try { |
| CentralDirectory dir = findCentralDirectory(raf); |
| |
| return computeCrcOfCentralDir(raf, dir); |
| } finally { |
| raf.close(); |
| } |
| } |
| |
| /* Package visible for testing */ |
| static CentralDirectory findCentralDirectory(RandomAccessFile raf) throws IOException, |
| ZipException { |
| long scanOffset = raf.length() - ENDHDR; |
| if (scanOffset < 0) { |
| throw new ZipException("File too short to be a zip file: " + raf.length()); |
| } |
| |
| long stopOffset = scanOffset - 0x10000 /* ".ZIP file comment"'s max length */; |
| if (stopOffset < 0) { |
| stopOffset = 0; |
| } |
| |
| int endSig = Integer.reverseBytes(ENDSIG); |
| while (true) { |
| raf.seek(scanOffset); |
| if (raf.readInt() == endSig) { |
| break; |
| } |
| |
| scanOffset--; |
| if (scanOffset < stopOffset) { |
| throw new ZipException("End Of Central Directory signature not found"); |
| } |
| } |
| // Read the End Of Central Directory. ENDHDR includes the signature |
| // bytes, |
| // which we've already read. |
| |
| // Pull out the information we need. |
| raf.skipBytes(2); // diskNumber |
| raf.skipBytes(2); // diskWithCentralDir |
| raf.skipBytes(2); // numEntries |
| raf.skipBytes(2); // totalNumEntries |
| CentralDirectory dir = new CentralDirectory(); |
| dir.size = Integer.reverseBytes(raf.readInt()) & 0xFFFFFFFFL; |
| dir.offset = Integer.reverseBytes(raf.readInt()) & 0xFFFFFFFFL; |
| return dir; |
| } |
| |
| /* Package visible for testing */ |
| static long computeCrcOfCentralDir(RandomAccessFile raf, CentralDirectory dir) |
| throws IOException { |
| CRC32 crc = new CRC32(); |
| long stillToRead = dir.size; |
| raf.seek(dir.offset); |
| int length = (int) Math.min(BUFFER_SIZE, stillToRead); |
| byte[] buffer = new byte[BUFFER_SIZE]; |
| length = raf.read(buffer, 0, length); |
| while (length != -1) { |
| crc.update(buffer, 0, length); |
| stillToRead -= length; |
| if (stillToRead == 0) { |
| break; |
| } |
| length = (int) Math.min(BUFFER_SIZE, stillToRead); |
| length = raf.read(buffer, 0, length); |
| } |
| return crc.getValue(); |
| } |
| } |