Handling gzip input buffer with zlib compressor

[kaarrot]

Hello, I'm having some problems while trying to decompress gzip buffer with zlib compressor. Can anybody give some guidance how to approach this please? I'm aware zlib requires explicit configuration to handle gzip with inflateInit2() but I'm not sure how to pass that. Can this be configured directly from blosc?

Here is a simplified example feeding in base64 input with Python.

import base64
import zlib
data = 'H4sIAAAAAAAAAHWPwQqCQBCGX0Xm7EFtK+smZBEUgXoLCdMhFtKV3akI8d0bLYmibvPPN3wz00CJxmQnTO41whwWQRIctmEcB6sQbFC3CjW3XW8kxpOpP+OC22d1Wml1qZkQGtoMsScxaczKN3plG8zlaHIta5KqWsozoTYw3/djzwhpLwivWFGHGpAFe7DL68JlBUk+l7KSN7tCOEJ4M3/qOI49vMHj+zCKdlFqLaU2ZHV2a4Ct/an0/ivdX8oYc1UVX860fQDQiMdxRQEAAA=='
print (zlib.decompress(base64.b64decode(data), 16 + zlib.MAX_WBITS).decode('utf-8'))

and the c++ version where blosc_decompress() returns 0 size:

#include <iostream>
#include <string>
#include <vector>

#include <blosc.h>
// #include <zlib.h>

using namespace std;

static std::string base64_decode(const std::string &in) {

    std::string out;

    std::vector<int> T(256,-1);
    for (int i=0; i<64; i++) T["ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/"[i]] = i; 

    int val=0, valb=-8;
    for (unsigned char c : in) {
        if (T[c] == -1) break;
        val = (val<<6) + T[c];
        valb += 6;
        if (valb>=0) {
            out.push_back(char((val>>valb)&0xFF));
            valb-=8;
        }
    }
    return out;
}

int main(){
        std::string s ="H4sIAAAAAAAAAHWPwQqCQBCGX0Xm7EFtK+smZBEUgXoLCdMhFtKV3akI8d0bLYmibvPPN3wz00CJxmQnTO41whwWQRIctmEcB6sQbFC3CjW3XW8kxpOpP+OC22d1Wml1qZkQGtoMsScxaczKN3plG8zlaHIta5KqWsozoTYw3/djzwhpLwivWFGHGpAFe7DL68JlBUk+l7KSN7tCOEJ4M3/qOI49vMHj+zCKdlFqLaU2ZHV2a4Ct/an0/ivdX8oYc1UVX860fQDQiMdxRQEAAA==";
    std::string dc = base64_decode(s);

    blosc_init();
    blosc_set_nthreads(1);

    int ret = blosc_set_compressor("zlib");
    cout << ret <<endl;

    char * data_dest = new char[dc.size() * 2]; 
    int dsize = blosc_decompress(dc.data(), data_dest, dc.size());
    cout << dsize <<endl;
    return 0;
}