mapnik/plugins/input/mbtiles_vector/vector_tile_compression.ipp
2025-04-05 09:35:31 +01:00

68 lines
2.6 KiB
C++

/**
* Copyright (c) MapBox
* All rights reserved.
*
* Redistribution and use in source and binary forms, with or without modification,
* are permitted provided that the following conditions are met:
*
* - Redistributions of source code must retain the above copyright notice, this
* list of conditions and the following disclaimer.
* - Redistributions in binary form must reproduce the above copyright notice, this
* list of conditions and the following disclaimer in the documentation and/or
* other materials provided with the distribution.
* - Neither the name "MapBox" nor the names of its contributors may be
* used to endorse or promote products derived from this software without
* specific prior written permission.
*
* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" AND
* ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
* WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
* DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE FOR
* ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
* (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
* LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON
* ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
* (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
* SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
*/
// zlib
#include <zlib.h>
// std
#include <stdexcept>
#include "vector_tile_compression.hpp"
// decodes both zlib and gzip
// http://stackoverflow.com/a/1838702/2333354
void mapnik::vector_tile_impl::zlib_decompress(const char * data, std::size_t size, std::string & output)
{
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;
inflateInit2(&inflate_s, 32 + 15);
inflate_s.next_in = (Bytef *)data;
inflate_s.avail_in = size;
size_t length = 0;
do {
output.resize(length + 2 * size);
inflate_s.avail_out = 2 * size;
inflate_s.next_out = (Bytef *)(output.data() + length);
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);
}
length += (2 * size - inflate_s.avail_out);
} while (inflate_s.avail_out == 0);
inflateEnd(&inflate_s);
output.resize(length);
}