kicad/thirdparty/gzip-hpp/decompress.hpp

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2020-11-19 06:06:05 +00:00
#ifndef GZIP_HPP_DECOMPRESS_HPP
#define GZIP_HPP_DECOMPRESS_HPP
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#ifndef ZLIB_CONST
#define ZLIB_CONST
#endif
// zlib
#include <zlib.h>
// std
#include <limits>
#include <stdexcept>
#include <string>
namespace gzip {
inline void decompress(const char* data,
std::size_t size,
std::string& output,
std::size_t max_uncompressed_size = 0,
std::size_t buffering_size = 0)
{
if (buffering_size == 0)
{
buffering_size = (size * 2) - (size / 2) + 16;
}
z_stream inflate_s;
inflate_s.zalloc = Z_NULL;
inflate_s.zfree = Z_NULL;
inflate_s.opaque = Z_NULL;
inflate_s.avail_in = 0;
inflate_s.next_in = Z_NULL;
// The windowBits parameter is the base two logarithm of the window size (the size of the history buffer).
// It should be in the range 8..15 for this version of the library.
// Larger values of this parameter result in better compression at the expense of memory usage.
// This range of values also changes the decoding type:
// -8 to -15 for raw deflate
// 8 to 15 for zlib
// (8 to 15) + 16 for gzip
// (8 to 15) + 32 to automatically detect gzip/zlib header
constexpr int window_bits = 15 + 32; // auto with windowbits of 15
constexpr unsigned int max_uint = std::numeric_limits<unsigned int>::max();
const unsigned int size_step = buffering_size > max_uint ? max_uint : static_cast<unsigned int>(buffering_size);
if( max_uncompressed_size != 0 && size_step > max_uncompressed_size )
{
throw std::runtime_error(
"buffer size used during decompression of gzip will use more memory then allowed, "
"either increase the limit or reduce the buffer size" );
}
#ifdef __GNUC__
#pragma GCC diagnostic push
#pragma GCC diagnostic ignored "-Wold-style-cast"
#endif
if (inflateInit2(&inflate_s, window_bits) != Z_OK)
{
throw std::runtime_error("inflate init failed");
}
#ifdef __GNUC__
#pragma GCC diagnostic pop
#endif
inflate_s.next_in = reinterpret_cast<z_const Bytef*>(data);
inflate_s.avail_in = static_cast<unsigned int>(size);
std::string buffer(static_cast<std::size_t>(size_step), char());
do
{
inflate_s.avail_out = size_step;
inflate_s.next_out = reinterpret_cast<Bytef*>(&buffer[0]);
const int ret = inflate(&inflate_s, Z_FINISH);
if (ret != Z_STREAM_END && ret != Z_OK && ret != Z_BUF_ERROR)
{
std::string error_msg = inflate_s.msg;
inflateEnd(&inflate_s);
throw std::runtime_error(error_msg);
}
if (max_uncompressed_size != 0 && (output.size() + size_step - inflate_s.avail_out) > max_uncompressed_size)
{
inflateEnd(&inflate_s);
throw std::runtime_error("size of output string will use more memory then intended when decompressing");
}
output.append(buffer, 0, size_step - inflate_s.avail_out);
} while (inflate_s.avail_out == 0);
const int ret2 = inflateEnd(&inflate_s);
if (ret2 != Z_OK)
{
throw std::runtime_error("Unexpected gzip decompression error, state of stream was inconsistent");
}
}
inline void decompress(std::string const& input,
std::string& output,
std::size_t max_uncompressed_size = 0,
std::size_t buffering_size = 0)
{
return decompress(input.data(), input.size(), output, max_uncompressed_size, buffering_size);
}
inline std::string decompress(const char* data,
std::size_t size,
std::size_t max_uncompressed_size = 0,
std::size_t buffering_size = 0)
{
std::string output;
decompress(data, size, output, max_uncompressed_size, buffering_size);
return output;
}
inline std::string decompress(std::string const& input,
std::size_t max_uncompressed_size = 0,
std::size_t buffering_size = 0)
{
std::string output;
decompress(input.data(), input.size(), output, max_uncompressed_size, buffering_size);
return output;
}
} // namespace gzip
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#endif // GZIP_HPP_DECOMPRESS_HPP