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/*
* CCompressedStream.h, 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
*
*/
#pragma once
#include "CInputStream.h"
struct z_stream_s;
VCMI_LIB_NAMESPACE_BEGIN
class DecompressionException : public std::runtime_error
{
public:
using runtime_error::runtime_error;
};
/// Abstract class that provides buffer for one-directional input streams (e.g. compressed data)
/// Used for zip archives support and in .lod deflate compression
class CBufferedStream : public CInputStream
{
public:
CBufferedStream();
/**
* Reads n bytes from the stream into the data buffer.
*
* @param data A pointer to the destination data array.
* @param size The number of bytes to read.
* @return the number of bytes read actually.
*
* @throws std::runtime_error if the file decompression was not successful
*/
si64 read(ui8 * data, si64 size) override;
/**
* Seeks the internal read pointer to the specified position.
* This will cause decompressing data till this position is found
*
* @param position The read position from the beginning.
* @return the position actually moved to, -1 on error.
*/
si64 seek(si64 position) override;
/**
* Gets the current read position in the stream.
*
* @return the read position.
*/
si64 tell() override;
/**
* Skips delta numbers of bytes.
*
* @param delta The count of bytes to skip.
* @return the count of bytes skipped actually.
*/
si64 skip(si64 delta) override;
/**
* Gets the length in bytes of the stream.
* Causes complete data decompression
*
* @return the length in bytes of the stream.
*/
si64 getSize() override;
protected:
/**
* @brief virtual method to get more data into the buffer
* @return amount of bytes actually read, non-positive values are considered to be end-of-file mark
*/
virtual si64 readMore(ui8 * data, si64 size) = 0;
/// resets all internal state
void reset();
private:
/// ensures that buffer contains at lest size of bytes. Calls readMore() to fill remaining part
void ensureSize(si64 size);
/** buffer with already decompressed data */
std::vector<ui8> buffer;
/** Current read position */
si64 position;
bool endOfFileReached;
};
/**
* A class which provides method definitions for reading a gzip-compressed file
* This class implements lazy loading - data will be decompressed (and cached) only by request
*/
class DLL_LINKAGE CCompressedStream : public CBufferedStream
{
public:
/**
* C-tor.
*
* @param stream - stream with compressed data
* @param gzip - this is gzipp'ed file e.g. campaign or maps, false for files in .lod
* @param decompressedSize - optional parameter to hint size of decompressed data
*/
CCompressedStream(std::unique_ptr<CInputStream> stream, bool gzip, size_t decompressedSize=0);
~CCompressedStream();
/**
* Prepare stream for decompression of next block (e.g. next part of h3c)
* Applicable only for streams that contain multiple concatenated compressed data
*
* @return false if next block was not found, true othervice
*/
bool getNextBlock();
private:
/**
* Decompresses data to ensure that buffer has newSize bytes or end of stream was reached
*/
si64 readMore(ui8 * data, si64 size) override;
/** The file stream with compressed data. */
std::unique_ptr<CInputStream> gzipStream;
/** buffer with not yet decompressed data*/
std::vector<ui8> compressedBuffer;
/** struct with current zlib inflate state */
z_stream_s * inflateState;
enum EState
{
ERROR_OCCURRED,
INITIALIZED,
IN_PROGRESS,
STREAM_END,
FINISHED
};
};
VCMI_LIB_NAMESPACE_END
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