1 /* 2 * Copyright (C) 2010 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 #ifndef __LIBS_STREAMINGZIPINFLATER_H 18 #define __LIBS_STREAMINGZIPINFLATER_H 19 20 #include <unistd.h> 21 #include <inttypes.h> 22 #include <zlib.h> 23 24 #include <utils/Compat.h> 25 26 namespace android { 27 28 class StreamingZipInflater { 29 public: 30 static const size_t INPUT_CHUNK_SIZE = 64 * 1024; 31 static const size_t OUTPUT_CHUNK_SIZE = 64 * 1024; 32 33 // Flavor that pages in the compressed data from a fd 34 StreamingZipInflater(int fd, off64_t compDataStart, size_t uncompSize, size_t compSize); 35 36 // Flavor that gets the compressed data from an in-memory buffer 37 StreamingZipInflater(class FileMap* dataMap, size_t uncompSize); 38 39 ~StreamingZipInflater(); 40 41 // read 'count' bytes of uncompressed data from the current position. outBuf may 42 // be NULL, in which case the data is consumed and discarded. 43 ssize_t read(void* outBuf, size_t count); 44 45 // seeking backwards requires uncompressing fom the beginning, so is very 46 // expensive. seeking forwards only requires uncompressing from the current 47 // position to the destination. 48 off64_t seekAbsolute(off64_t absoluteInputPosition); 49 50 private: 51 void initInflateState(); 52 int readNextChunk(); 53 54 // where to find the uncompressed data 55 int mFd; 56 off64_t mInFileStart; // where the compressed data lives in the file 57 class FileMap* mDataMap; 58 59 z_stream mInflateState; 60 bool mStreamNeedsInit; 61 62 // output invariants for this asset 63 uint8_t* mOutBuf; // output buf for decompressed bytes 64 size_t mOutBufSize; // allocated size of mOutBuf 65 size_t mOutTotalSize; // total uncompressed size of the blob 66 67 // current output state bookkeeping 68 off64_t mOutCurPosition; // current position in total offset 69 size_t mOutLastDecoded; // last decoded byte + 1 in mOutbuf 70 size_t mOutDeliverable; // next undelivered byte of decoded output in mOutBuf 71 72 // input invariants 73 uint8_t* mInBuf; 74 size_t mInBufSize; // allocated size of mInBuf; 75 size_t mInTotalSize; // total size of compressed data for this blob 76 77 // input state bookkeeping 78 size_t mInNextChunkOffset; // offset from start of blob at which the next input chunk lies 79 // the z_stream contains state about input block consumption 80 }; 81 82 } 83 84 #endif 85