226 lines
7.8 KiB
C++
226 lines
7.8 KiB
C++
/*
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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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#define LOG_TAG "szipinf"
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#include <utils/Log.h>
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#include <utils/FileMap.h>
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#include <utils/StreamingZipInflater.h>
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#include <string.h>
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#include <unistd.h>
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#include <assert.h>
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static inline size_t min(size_t a, size_t b) { return (a < b) ? a : b; }
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using namespace android;
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/*
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* Streaming access to compressed asset data in an open fd
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*/
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StreamingZipInflater::StreamingZipInflater(int fd, off_t compDataStart,
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size_t uncompSize, size_t compSize) {
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mFd = fd;
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mDataMap = NULL;
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mInFileStart = compDataStart;
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mOutTotalSize = uncompSize;
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mInTotalSize = compSize;
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mInBufSize = StreamingZipInflater::INPUT_CHUNK_SIZE;
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mInBuf = new uint8_t[mInBufSize];
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mOutBufSize = StreamingZipInflater::OUTPUT_CHUNK_SIZE;
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mOutBuf = new uint8_t[mOutBufSize];
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initInflateState();
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}
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/*
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* Streaming access to compressed data held in an mmapped region of memory
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*/
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StreamingZipInflater::StreamingZipInflater(FileMap* dataMap, size_t uncompSize) {
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mFd = -1;
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mDataMap = dataMap;
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mOutTotalSize = uncompSize;
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mInTotalSize = dataMap->getDataLength();
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mInBuf = (uint8_t*) dataMap->getDataPtr();
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mInBufSize = mInTotalSize;
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mOutBufSize = StreamingZipInflater::OUTPUT_CHUNK_SIZE;
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mOutBuf = new uint8_t[mOutBufSize];
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initInflateState();
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}
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StreamingZipInflater::~StreamingZipInflater() {
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// tear down the in-flight zip state just in case
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::inflateEnd(&mInflateState);
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if (mDataMap == NULL) {
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delete [] mInBuf;
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}
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delete [] mOutBuf;
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}
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void StreamingZipInflater::initInflateState() {
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LOGD("Initializing inflate state");
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memset(&mInflateState, 0, sizeof(mInflateState));
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mInflateState.zalloc = Z_NULL;
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mInflateState.zfree = Z_NULL;
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mInflateState.opaque = Z_NULL;
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mInflateState.next_in = (Bytef*)mInBuf;
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mInflateState.next_out = (Bytef*) mOutBuf;
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mInflateState.avail_out = mOutBufSize;
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mInflateState.data_type = Z_UNKNOWN;
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mOutLastDecoded = mOutDeliverable = mOutCurPosition = 0;
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mInNextChunkOffset = 0;
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mStreamNeedsInit = true;
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if (mDataMap == NULL) {
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::lseek(mFd, mInFileStart, SEEK_SET);
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mInflateState.avail_in = 0; // set when a chunk is read in
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} else {
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mInflateState.avail_in = mInBufSize;
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}
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}
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/*
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* Basic approach:
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*
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* 1. If we have undelivered uncompressed data, send it. At this point
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* either we've satisfied the request, or we've exhausted the available
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* output data in mOutBuf.
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*
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* 2. While we haven't sent enough data to satisfy the request:
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* 0. if the request is for more data than exists, bail.
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* a. if there is no input data to decode, read some into the input buffer
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* and readjust the z_stream input pointers
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* b. point the output to the start of the output buffer and decode what we can
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* c. deliver whatever output data we can
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*/
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ssize_t StreamingZipInflater::read(void* outBuf, size_t count) {
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uint8_t* dest = (uint8_t*) outBuf;
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size_t bytesRead = 0;
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size_t toRead = min(count, size_t(mOutTotalSize - mOutCurPosition));
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while (toRead > 0) {
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// First, write from whatever we already have decoded and ready to go
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size_t deliverable = min(toRead, mOutLastDecoded - mOutDeliverable);
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if (deliverable > 0) {
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if (outBuf != NULL) memcpy(dest, mOutBuf + mOutDeliverable, deliverable);
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mOutDeliverable += deliverable;
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mOutCurPosition += deliverable;
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dest += deliverable;
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bytesRead += deliverable;
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toRead -= deliverable;
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}
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// need more data? time to decode some.
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if (toRead > 0) {
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// if we don't have any data to decode, read some in. If we're working
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// from mmapped data this won't happen, because the clipping to total size
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// will prevent reading off the end of the mapped input chunk.
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if (mInflateState.avail_in == 0) {
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int err = readNextChunk();
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if (err < 0) {
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LOGE("Unable to access asset data: %d", err);
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if (!mStreamNeedsInit) {
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::inflateEnd(&mInflateState);
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initInflateState();
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}
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return -1;
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}
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}
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// we know we've drained whatever is in the out buffer now, so just
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// start from scratch there, reading all the input we have at present.
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mInflateState.next_out = (Bytef*) mOutBuf;
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mInflateState.avail_out = mOutBufSize;
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/*
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LOGD("Inflating to outbuf: avail_in=%u avail_out=%u next_in=%p next_out=%p",
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mInflateState.avail_in, mInflateState.avail_out,
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mInflateState.next_in, mInflateState.next_out);
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*/
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int result = Z_OK;
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if (mStreamNeedsInit) {
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LOGI("Initializing zlib to inflate");
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result = inflateInit2(&mInflateState, -MAX_WBITS);
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mStreamNeedsInit = false;
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}
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if (result == Z_OK) result = ::inflate(&mInflateState, Z_SYNC_FLUSH);
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if (result < 0) {
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// Whoops, inflation failed
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LOGE("Error inflating asset: %d", result);
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::inflateEnd(&mInflateState);
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initInflateState();
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return -1;
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} else {
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if (result == Z_STREAM_END) {
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// we know we have to have reached the target size here and will
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// not try to read any further, so just wind things up.
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::inflateEnd(&mInflateState);
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}
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// Note how much data we got, and off we go
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mOutDeliverable = 0;
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mOutLastDecoded = mOutBufSize - mInflateState.avail_out;
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}
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}
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}
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return bytesRead;
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}
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int StreamingZipInflater::readNextChunk() {
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assert(mDataMap == NULL);
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if (mInNextChunkOffset < mInTotalSize) {
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size_t toRead = min(mInBufSize, mInTotalSize - mInNextChunkOffset);
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if (toRead > 0) {
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ssize_t didRead = ::read(mFd, mInBuf, toRead);
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//LOGD("Reading input chunk, size %08x didread %08x", toRead, didRead);
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if (didRead < 0) {
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// TODO: error
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LOGE("Error reading asset data");
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return didRead;
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} else {
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mInNextChunkOffset += didRead;
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mInflateState.next_in = (Bytef*) mInBuf;
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mInflateState.avail_in = didRead;
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}
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}
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}
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return 0;
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}
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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 StreamingZipInflater::seekAbsolute(off_t absoluteInputPosition) {
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if (absoluteInputPosition < mOutCurPosition) {
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// rewind and reprocess the data from the beginning
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if (!mStreamNeedsInit) {
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::inflateEnd(&mInflateState);
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}
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initInflateState();
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read(NULL, absoluteInputPosition);
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} else if (absoluteInputPosition > mOutCurPosition) {
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read(NULL, absoluteInputPosition - mOutCurPosition);
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}
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// else if the target position *is* our current position, do nothing
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return absoluteInputPosition;
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}
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