Function gzipCompress

Sources/Dependencies/ixwebsocket/IXGzipCodec.cpp:19–64

namespace ix
{
	std::string gzipCompress(const std::string& str)
	{
#ifndef IXWEBSOCKET_USE_ZLIB
		return std::string();
#else
		z_stream zs; // z_stream is zlib's control structure
		memset(&zs, 0, sizeof(zs));

		// deflateInit2 configure the file format: request gzip instead of deflate
		const int windowBits = 15;
		const int GZIP_ENCODING = 16;

		deflateInit2(&zs,
					 Z_DEFAULT_COMPRESSION,
					 Z_DEFLATED,
					 windowBits | GZIP_ENCODING,
					 8,
					 Z_DEFAULT_STRATEGY);

		zs.next_in = (Bytef*) str.data();
		zs.avail_in = (uInt) str.size(); // set the z_stream's input

		int ret;
		char outbuffer[32768];
		std::string outstring;

		// retrieve the compressed bytes blockwise
		do
		{
			zs.next_out = reinterpret_cast<Bytef*>(outbuffer);
			zs.avail_out = sizeof(outbuffer);

			ret = deflate(&zs, Z_FINISH);

			if (outstring.size() < zs.total_out)
			{
				// append the block to the output string
				outstring.append(outbuffer, zs.total_out - outstring.size());
			}
		} while (ret == Z_OK);

		deflateEnd(&zs);

		return outstring;
#endif
	}

#ifdef IXWEBSOCKET_USE_DEFLATE
	static uint32_t loadDecompressedGzipSize(const uint8_t* p)