#include <string>
#include <sstream>
#include <stdexcept>
#include <string.h>
#include "zlib.h"
using std::string;
using std::stringstream;
// Found these here http://mail-archives.apache.org/mod_mbox/trafficserver-dev/201110.mbox/%3CCACJPjhYf=+br1W39vyazP=ix
//eQZ-4Gh9-U6TtiEdReG3S4ZZng@mail.gmail.com%3E
#define MOD_GZIP_ZLIB_WINDOWSIZE 15
#define MOD_GZIP_ZLIB_CFACTOR 9
#define MOD_GZIP_ZLIB_BSIZE 8096
// Found this one here: http://panthema.net/2007/0328-ZLibString.html, author is Timo Bingmann
// edited version
/** Compress a STL string using zlib with given compression level and return
* the binary data. */
std::string compress_gzip(const std::string& str,
int compressionlevel = Z_BEST_COMPRESSION)
{
z_stream zs; // z_stream is zlib's control structure
memset(&zs, 0, sizeof(zs));
if (deflateInit2(&zs,
compressionlevel,
Z_DEFLATED,
MOD_GZIP_ZLIB_WINDOWSIZE + 16,
MOD_GZIP_ZLIB_CFACTOR,
Z_DEFAULT_STRATEGY) != Z_OK
) {
throw(std::runtime_error("deflateInit2 failed while compressing."));
}
zs.next_in = (Bytef*)str.data();
zs.avail_in = 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);
if (ret != Z_STREAM_END) { // an error occurred that was not EOF
std::ostringstream oss;
oss << "Exception during zlib compression: (" << ret << ") " << zs.msg;
throw(std::runtime_error(oss.str()));
}
return outstring;
}
// Found this one here: http://panthema.net/2007/0328-ZLibString.html, author is Timo Bingmann
/** Compress a STL string using zlib with given compression level and return
* the binary data. */
std::string compress_deflate(const std::string& str,
int compressionlevel = Z_BEST_COMPRESSION)
{
z_stream zs; // z_stream is zlib's control structure
memset(&zs, 0, sizeof(zs));
if (deflateInit(&zs, compressionlevel) != Z_OK)
throw(std::runtime_error("deflateInit failed while compressing."));
zs.next_in = (Bytef*)str.data();
zs.avail_in = 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);
if (ret != Z_STREAM_END) { // an error occurred that was not EOF
std::ostringstream oss;
oss << "Exception during zlib compression: (" << ret << ") " << zs.msg;
throw(std::runtime_error(oss.str()));
}
return outstring;
}
/** Decompress an STL string using zlib and return the original data. */
std::string decompress_deflate(const std::string& str)
{
z_stream zs; // z_stream is zlib's control structure
memset(&zs, 0, sizeof(zs));
if (inflateInit(&zs) != Z_OK)
throw(std::runtime_error("inflateInit failed while decompressing."));
zs.next_in = (Bytef*)str.data();
zs.avail_in = str.size();
int ret;
char outbuffer[32768];
std::string outstring;
// get the decompressed bytes blockwise using repeated calls to inflate
do {
zs.next_out = reinterpret_cast<Bytef*>(outbuffer);
zs.avail_out = sizeof(outbuffer);
ret = inflate(&zs, 0);
if (outstring.size() < zs.total_out) {
outstring.append(outbuffer,
zs.total_out - outstring.size());
}
} while (ret == Z_OK);
inflateEnd(&zs);
if (ret != Z_STREAM_END) { // an error occurred that was not EOF
std::ostringstream oss;
oss << "Exception during zlib decompression: (" << ret << ") "
<< zs.msg;
throw(std::runtime_error(oss.str()));
}
return outstring;
}
std::string decompress_gzip(const std::string& str)
{
z_stream zs; // z_stream is zlib's control structure
memset(&zs, 0, sizeof(zs));
if (inflateInit2(&zs, MOD_GZIP_ZLIB_WINDOWSIZE + 16) != Z_OK)
throw(std::runtime_error("inflateInit failed while decompressing."));
zs.next_in = (Bytef*)str.data();
zs.avail_in = str.size();
int ret;
char outbuffer[32768];
std::string outstring;
// get the decompressed bytes blockwise using repeated calls to inflate
do {
zs.next_out = reinterpret_cast<Bytef*>(outbuffer);
zs.avail_out = sizeof(outbuffer);
ret = inflate(&zs, 0);
if (outstring.size() < zs.total_out) {
outstring.append(outbuffer,
zs.total_out - outstring.size());
}
} while (ret == Z_OK);
inflateEnd(&zs);
if (ret != Z_STREAM_END) { // an error occurred that was not EOF
std::ostringstream oss;
oss << "Exception during zlib decompression: (" << ret << ") "
<< zs.msg;
throw(std::runtime_error(oss.str()));
}
return outstring;
}
// Compile: g++ -std=c++11 % -lz
// Run: ./a.out
#include <iostream>
int main()
{
std::string s = "Hello";
std::cout << "input: " << s << std::endl;
std::cout << "gzip compressed: " << compress_gzip(s) << std::endl;;
std::cout << "gzip decompressed: " << decompress_gzip(compress_gzip(s)) << std::endl;;
std::cout << "deflate compressed: " << compress_deflate(s) << std::endl;;
std::cout << "deflate decompressed: " << decompress_deflate(compress_deflate(s)) << std::endl;;
}
