minetestmapper/ZlibDecompressor.cpp
2024-04-20 21:38:05 +02:00

70 lines
1.3 KiB
C++

#include <zlib.h>
#include <stdint.h>
#include "ZlibDecompressor.h"
ZlibDecompressor::ZlibDecompressor(const u8 *data, size_t size):
m_data(data),
m_seekPos(0),
m_size(size)
{
}
ZlibDecompressor::~ZlibDecompressor()
{
}
void ZlibDecompressor::setSeekPos(size_t seekPos)
{
m_seekPos = seekPos;
}
size_t ZlibDecompressor::seekPos() const
{
return m_seekPos;
}
ustring ZlibDecompressor::decompress()
{
const unsigned char *data = m_data + m_seekPos;
const size_t size = m_size - m_seekPos;
ustring buffer;
constexpr size_t BUFSIZE = 32 * 1024;
z_stream strm;
strm.zalloc = Z_NULL;
strm.zfree = Z_NULL;
strm.opaque = Z_NULL;
strm.next_in = Z_NULL;
strm.avail_in = 0;
if (inflateInit(&strm) != Z_OK)
throw DecompressError();
strm.next_in = const_cast<unsigned char *>(data);
strm.avail_in = size;
buffer.resize(BUFSIZE);
strm.next_out = &buffer[0];
strm.avail_out = BUFSIZE;
int ret = 0;
do {
ret = inflate(&strm, Z_NO_FLUSH);
if (strm.avail_out == 0) {
const auto off = buffer.size();
buffer.reserve(off + BUFSIZE);
strm.next_out = &buffer[off];
strm.avail_out = BUFSIZE;
}
} while (ret == Z_OK);
if (ret != Z_STREAM_END)
throw DecompressError();
m_seekPos += strm.next_in - data;
buffer.resize(buffer.size() - strm.avail_out);
(void) inflateEnd(&strm);
return buffer;
}