106 lines
2.6 KiB
C++
106 lines
2.6 KiB
C++
// Little utility functions for data compression.
|
|
// Taken from http://panthema.net/2007/0328-ZLibString.html
|
|
|
|
|
|
#include <string>
|
|
#include <stdexcept>
|
|
#include <iostream>
|
|
#include <iomanip>
|
|
#include <sstream>
|
|
#include <cstring>
|
|
|
|
#include <zlib.h>
|
|
|
|
#include "base/logging.h"
|
|
|
|
/** Compress a STL string using zlib with given compression level and return
|
|
* the binary data. */
|
|
bool compress_string(const std::string& str, std::string *dest, int compressionlevel) {
|
|
z_stream zs; // z_stream is zlib's control structure
|
|
memset(&zs, 0, sizeof(zs));
|
|
|
|
if (deflateInit(&zs, compressionlevel) != Z_OK) {
|
|
ELOG("deflateInit failed while compressing.");
|
|
return false;
|
|
}
|
|
|
|
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;
|
|
return false;
|
|
}
|
|
|
|
*dest = outstring;
|
|
return true;
|
|
}
|
|
|
|
/** Decompress an STL string using zlib and return the original data. */
|
|
bool decompress_string(const std::string& str, std::string *dest) {
|
|
if (!str.size())
|
|
return false;
|
|
|
|
z_stream zs; // z_stream is zlib's control structure
|
|
memset(&zs, 0, sizeof(zs));
|
|
|
|
// modification by hrydgard: inflateInit2, 16+MAXWBITS makes it read gzip data too
|
|
if (inflateInit2(&zs, 32+MAX_WBITS) != Z_OK) {
|
|
ELOG("inflateInit failed while decompressing.");
|
|
return false;
|
|
}
|
|
|
|
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;
|
|
ELOG("Exception during zlib decompression: (%i) %s", ret, zs.msg);
|
|
return false;
|
|
}
|
|
|
|
*dest = outstring;
|
|
return true;
|
|
}
|