QNetworkAccessManager with Accept-Encoding gzip

[patrik08]

I subclass QNetworkAccessManager (This class was introduced in Qt 4.4.) to load remote xml html or image to compose documents.

the code is avaiable on:

http://fop-miniscribus.googlecode.com/svn/trunk/fop_miniscribus.2.0.0/src/format_network/FillCache.h
http://fop-miniscribus.googlecode.com/svn/trunk/fop_miniscribus.2.0.0/src/format_network/FillCache.cpp

I start request on this way:




void NetCacheSwap::start_Get( const QUrl url )
{
CacheInfo havingram = take_Url(url);
if (havingram.pending) {
/* request ist start */
return;
}
if (havingram.valid) {
/* request and data live on swap cache */
emit incomming(url);
return;
}
CacheInfo newrequest;
QNetworkRequest need(url);
need.setRawHeader( "User-Agent", "Mozilla/5.0 (X11; U; Linux i686 (x86_64); "
"en-US; rv:1.9.0.1) Gecko/2008070206 Firefox/3.0.1" );
need.setRawHeader( "Accept-Charset", "ISO-8859-1,utf-8;q=0.7,*;q=0.7" );
need.setRawHeader( "Accept-Encoding", "gzip,deflate,qcompress" ); ////////gzip,deflate,qcompress
need.setRawHeader( "Connection", "keep-alive" );
if (cookie_host[url.host()].size() > 0) {
qDebug() << "### > send cookie ->" << cookie_host[url.host()].toAscii();
need.setRawHeader( "Cookie",cookie_host[url.host()].toAscii());
}
QNetworkReply *reps = get(need);
/* mark it as pending request! */
newrequest.pending = true;
cache_ram.insert(fastmd5(url.toString()),newreques t);
connect(reps, SIGNAL(downloadProgress (qint64,qint64)),
SLOT(progress(qint64,qint64)));
connect(reps, SIGNAL(error(QNetworkReply::NetworkError)),
SLOT(url_error(QNetworkReply::NetworkError)));
connect(reps, SIGNAL(finished()),SLOT(incomming_cache()));
}



if incomming chunk is and header is content-encoding == gzip i open on this way:

i decompress on file .....



QByteArray NetCacheSwap::deflate( const QByteArray chunk )
{
QChar letter('A' + (qrand() % 26));
/* must not go on file solution gunzip buffer ? go cache from net location */
const QString tmpfiler = QString("%1/http_%2.gz").arg(location).arg(letter);
QByteArray input;
QFile file(tmpfiler);
if ( file.open(QIODevice::WriteOnly) ) {
file.write(chunk);
file.close();
gzFile filegunzip;
filegunzip = gzopen(tmpfiler.toUtf8().data(),"rb");
if(!filegunzip) {
qDebug() << "### Unable to work on tmp file ... ";
return QByteArray();
}
char buffer[1024];
while(int readBytes =gzread(filegunzip, buffer, 1024))
{
input.append(QByteArray(buffer, readBytes));
}
gzclose(filegunzip);
file.remove();
}
return input;
}




How i can deflate / decompress QByteArray data direct on buffer? is this possibel?


i search "content-encoding" on network qt lib i found only

bool QHttpNetworkReplyPrivate::isGzipped()
{
QByteArray encoding = headerField("content-encoding");
return encoding.toLower() == "gzip";
}

and isGzipped search is NULL on other or webkit .. ?

[patrik08]

is this not possibel to deflate on buffer?

[DavidWoo]

Theres a solution here with code that decompresses gzip data using zlib:

http://stackoverflow.com/questions/2690328/qt-quncompress-gzip-data


QByteArray gUncompress(const QByteArray &data)
{
if (data.size() <= 4) {
qWarning("gUncompress: Input data is truncated");
return QByteArray();
}

QByteArray result;

int ret;
z_stream strm;
static const int CHUNK_SIZE = 1024;
char out[CHUNK_SIZE];

/* allocate inflate state */
strm.zalloc = Z_NULL;
strm.zfree = Z_NULL;
strm.opaque = Z_NULL;
strm.avail_in = data.size();
strm.next_in = (Bytef*)(data.data());

ret = inflateInit2(&strm, 15 + 32); // gzip decoding
if (ret != Z_OK)
return QByteArray();

// run inflate()
do {
strm.avail_out = CHUNK_SIZE;
strm.next_out = (Bytef*)(out);

ret = inflate(&strm, Z_NO_FLUSH);
Q_ASSERT(ret != Z_STREAM_ERROR); // state not clobbered

switch (ret) {
case Z_NEED_DICT:
ret = Z_DATA_ERROR; // and fall through
case Z_DATA_ERROR:
case Z_MEM_ERROR:
(void)inflateEnd(&strm);
return QByteArray();
}

result.append(out, CHUNK_SIZE - strm.avail_out);
} while (strm.avail_out == 0);

// clean up and return
inflateEnd(&strm);
return result;
}