83 lines
2.8 KiB
C
83 lines
2.8 KiB
C
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/*
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* Copyright (C) 2010 The Android Open Source Project
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*
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* Licensed under the Apache License, Version 2.0 (the "License");
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* you may not use this file except in compliance with the License.
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* You may obtain a copy of the License at
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*
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* http://www.apache.org/licenses/LICENSE-2.0
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*
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* Unless required by applicable law or agreed to in writing, software
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* distributed under the License is distributed on an "AS IS" BASIS,
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* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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* See the License for the specific language governing permissions and
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* limitations under the License.
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*/
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#ifndef __LIBS_STREAMINGZIPINFLATER_H
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#define __LIBS_STREAMINGZIPINFLATER_H
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#include <unistd.h>
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#include <inttypes.h>
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#include <zlib.h>
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namespace android {
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class StreamingZipInflater {
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public:
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static const size_t INPUT_CHUNK_SIZE = 64 * 1024;
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static const size_t OUTPUT_CHUNK_SIZE = 64 * 1024;
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// Flavor that pages in the compressed data from a fd
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StreamingZipInflater(int fd, off_t compDataStart, size_t uncompSize, size_t compSize);
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// Flavor that gets the compressed data from an in-memory buffer
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StreamingZipInflater(class FileMap* dataMap, size_t uncompSize);
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~StreamingZipInflater();
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// read 'count' bytes of uncompressed data from the current position. outBuf may
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// be NULL, in which case the data is consumed and discarded.
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ssize_t read(void* outBuf, size_t count);
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// seeking backwards requires uncompressing fom the beginning, so is very
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// expensive. seeking forwards only requires uncompressing from the current
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// position to the destination.
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off_t seekAbsolute(off_t absoluteInputPosition);
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private:
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void initInflateState();
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int readNextChunk();
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// where to find the uncompressed data
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int mFd;
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off_t mInFileStart; // where the compressed data lives in the file
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class FileMap* mDataMap;
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z_stream mInflateState;
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bool mStreamNeedsInit;
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// output invariants for this asset
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uint8_t* mOutBuf; // output buf for decompressed bytes
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size_t mOutBufSize; // allocated size of mOutBuf
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size_t mOutTotalSize; // total uncompressed size of the blob
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// current output state bookkeeping
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off_t mOutCurPosition; // current position in total offset
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size_t mOutLastDecoded; // last decoded byte + 1 in mOutbuf
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size_t mOutDeliverable; // next undelivered byte of decoded output in mOutBuf
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// input invariants
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uint8_t* mInBuf;
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size_t mInBufSize; // allocated size of mInBuf;
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size_t mInTotalSize; // total size of compressed data for this blob
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// input state bookkeeping
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size_t mInNextChunkOffset; // offset from start of blob at which the next input chunk lies
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// the z_stream contains state about input block consumption
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};
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}
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#endif
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