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/*
* Copyright (C) 2010 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.
*/
#ifndef __LIBS_STREAMINGZIPINFLATER_H
#define __LIBS_STREAMINGZIPINFLATER_H
#include <unistd.h>
#include <inttypes.h>
#include <zlib.h>
#include <utils/Compat.h>
namespace android {
class StreamingZipInflater {
public:
static const size_t INPUT_CHUNK_SIZE = 64 * 1024;
static const size_t OUTPUT_CHUNK_SIZE = 64 * 1024;
// Flavor that pages in the compressed data from a fd
StreamingZipInflater(int fd, off64_t compDataStart, size_t uncompSize, size_t compSize);
// Flavor that gets the compressed data from an in-memory buffer
StreamingZipInflater(class FileMap* dataMap, size_t uncompSize);
~StreamingZipInflater();
// read 'count' bytes of uncompressed data from the current position. outBuf may
// be NULL, in which case the data is consumed and discarded.
ssize_t read(void* outBuf, size_t count);
// seeking backwards requires uncompressing fom the beginning, so is very
// expensive. seeking forwards only requires uncompressing from the current
// position to the destination.
off64_t seekAbsolute(off64_t absoluteInputPosition);
private:
void initInflateState();
int readNextChunk();
// where to find the uncompressed data
int mFd;
off64_t mInFileStart; // where the compressed data lives in the file
class FileMap* mDataMap;
z_stream mInflateState;
bool mStreamNeedsInit;
// output invariants for this asset
uint8_t* mOutBuf; // output buf for decompressed bytes
size_t mOutBufSize; // allocated size of mOutBuf
size_t mOutTotalSize; // total uncompressed size of the blob
// current output state bookkeeping
off64_t mOutCurPosition; // current position in total offset
size_t mOutLastDecoded; // last decoded byte + 1 in mOutbuf
size_t mOutDeliverable; // next undelivered byte of decoded output in mOutBuf
// input invariants
uint8_t* mInBuf;
size_t mInBufSize; // allocated size of mInBuf;
size_t mInTotalSize; // total size of compressed data for this blob
// input state bookkeeping
size_t mInNextChunkOffset; // offset from start of blob at which the next input chunk lies
// the z_stream contains state about input block consumption
};
}
#endif
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