Hello, I stumble upon a problem, and can't find a solution.

So what I want to do is uncompress data in qt, using qUncompress(QByteArray), send from www in gzip format. I used wireshark to determine that this is valid gzip stream, also tested with zip/rar and both can uncompress it.

Code so far, is like this:

    static const char dat[40] = {
         0x1f, 0x8b, 0x08, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x03, 0xaa, 0x2e, 0x2e, 0x49, 0x2c, 0x29,
         0x2d, 0xb6, 0x4a, 0x4b, 0xcc, 0x29, 0x4e, 0xad, 0x05, 0x00, 0x00, 0x00, 0xff, 0xff, 0x03, 0x00,
         0x2a, 0x63, 0x18, 0xc5, 0x0e, 0x00, 0x00, 0x00
    };
//this data contains string: {status:false}, in gzip format
QByteArray data;
           data.append( dat, sizeof(dat) );

unsigned int size = 14; //expected uncompresed size, reconstruct it BigEndianes

//prepand expected uncompressed size, last 4 byte in dat 0x0e = 14
QByteArray dataPlusSize;

dataPlusSize.append( (unsigned int)((size >> 24) & 0xFF));
dataPlusSize.append( (unsigned int)((size >> 16) & 0xFF));
dataPlusSize.append( (unsigned int)((size >> 8) & 0xFF));
dataPlusSize.append( (unsigned int)((size >> 0) & 0xFF));

QByteArray uncomp = qUncompress( dataPlusSize );
qDebug() << uncomp;

And uncompression fails with: qUncompress: Z_DATA_ERROR: Input data is corrupted.

AFAIK gzip consist of 10 byte header, DEFLATE peyload, 12 byte trailer ( 8 byte CRC32 + 4 byte ISIZE - uncompresed data size ). Striping header and trailer should leave me with DEFLATE data stream, qUncompress yields same error.

I checked with data string compressed in PHP, like this:

$stringData = gzcompress( "{status:false}", 1);

and qUncompress uncompress that data.(I didn't see and gzip header though i.e. ID1 = 0x1f, ID2 = 0x8b ) I checked above code with debug, and error occurs at:

        if (
        #endif
            ((BITS(8) << 8) + (hold >> 8)) % 31) { //here is error, WHY? long unsigned int hold = 35615
            strm->msg = (char *)"incorrect header check";
            state->mode = BAD;
            break;
        } 

inflate.c line 610.

I know that qUncompress is simply a wrapper to zlib, so I suppose it should handle gzip without any problem. Any comments are more then welcome.

Best regards