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