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vcmi/lib/filesystem/CCompressedStream.cpp

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/*
* CCompressedStream.cpp, part of VCMI engine
*
* Authors: listed in file AUTHORS in main folder
*
* License: GNU General Public License v2.0 or later
* Full text of license available in license.txt file, in main folder
*
*/
#include "StdInc.h"
#include "CCompressedStream.h"
#include <zlib.h>
static const int inflateBlockSize = 10000;
CBufferedStream::CBufferedStream():
position(0),
endOfFileReached(false)
{
}
si64 CBufferedStream::read(ui8 * data, si64 size)
{
ensureSize(position + size);
auto start = buffer.data() + position;
si64 toRead = std::min<si64>(size, buffer.size() - position);
std::copy(start, start + toRead, data);
position += toRead;
return size;
}
si64 CBufferedStream::seek(si64 position)
{
ensureSize(position);
this->position = std::min<si64>(position, buffer.size());
return this->position;
}
si64 CBufferedStream::tell()
{
return position;
}
si64 CBufferedStream::skip(si64 delta)
{
return seek(position + delta) - delta;
}
si64 CBufferedStream::getSize()
{
si64 prevPos = tell();
seek(std::numeric_limits<si64>::max());
si64 size = tell();
seek(prevPos);
return size;
}
void CBufferedStream::ensureSize(si64 size)
{
while (buffer.size() < size && !endOfFileReached)
{
si64 initialSize = buffer.size();
si64 currentStep = std::min<si64>(size, buffer.size());
vstd::amax(currentStep, 1024); // to avoid large number of calls at start
buffer.resize(initialSize + currentStep);
si64 readSize = readMore(buffer.data() + initialSize, currentStep);
if (readSize != currentStep)
{
endOfFileReached = true;
buffer.resize(initialSize + readSize);
buffer.shrink_to_fit();
return;
}
}
}
void CBufferedStream::reset()
{
buffer.clear();
position = 0;
endOfFileReached = false;
}
CCompressedStream::CCompressedStream(std::unique_ptr<CInputStream> stream, bool gzip, size_t decompressedSize):
gzipStream(std::move(stream)),
compressedBuffer(inflateBlockSize)
{
assert(gzipStream);
// Allocate inflate state
inflateState = new z_stream;
inflateState->zalloc = Z_NULL;
inflateState->zfree = Z_NULL;
inflateState->opaque = Z_NULL;
inflateState->avail_in = 0;
inflateState->next_in = Z_NULL;
int wbits = 15;
if (gzip)
wbits += 16;
int ret = inflateInit2(inflateState, wbits);
if (ret != Z_OK)
throw std::runtime_error("Failed to initialize inflate!\n");
}
CCompressedStream::~CCompressedStream()
{
inflateEnd(inflateState);
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vstd::clear_pointer(inflateState);
}
si64 CCompressedStream::readMore(ui8 *data, si64 size)
{
if (inflateState == nullptr)
return 0; //file already decompressed
bool fileEnded = false; //end of file reached
bool endLoop = false;
int decompressed = inflateState->total_out;
inflateState->avail_out = size;
inflateState->next_out = data;
do
{
if (inflateState->avail_in == 0)
{
//inflate ran out of available data or was not initialized yet
// get new input data and update state accordingly
si64 availSize = gzipStream->read(compressedBuffer.data(), compressedBuffer.size());
if (availSize != compressedBuffer.size())
gzipStream.reset();
inflateState->avail_in = availSize;
inflateState->next_in = compressedBuffer.data();
}
int ret = inflate(inflateState, Z_NO_FLUSH);
if (inflateState->avail_in == 0 && gzipStream == nullptr)
fileEnded = true;
switch (ret)
{
case Z_OK: //input data ended/ output buffer full
endLoop = false;
break;
case Z_STREAM_END: // stream ended. Note that campaign files consist from multiple such streams
endLoop = true;
break;
case Z_BUF_ERROR: // output buffer full. Can be triggered?
endLoop = true;
break;
default:
if (inflateState->msg == nullptr)
throw std::runtime_error("Decompression error. Return code was " + boost::lexical_cast<std::string>(ret));
else
throw std::runtime_error(std::string("Decompression error: ") + inflateState->msg);
}
}
while (endLoop == false && inflateState->avail_out != 0 );
decompressed = inflateState->total_out - decompressed;
// Clean up and return
if (fileEnded)
{
inflateEnd(inflateState);
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vstd::clear_pointer(inflateState);
}
return decompressed;
}
bool CCompressedStream::getNextBlock()
{
if (!inflateState)
return false;
if (inflateReset(inflateState) < 0)
return false;
reset();
return true;
}