Fix error handling in write for socks socket engine

When socks socket engine calls the write function of the native socket
engine, it now propagates errors to the abstract socket.

Task-number: QTBUG-18713
Reviewed-by: Markus Goetz

1 files changed, 6 insertions, 1 deletions

diff --git a/src/network/socket/qsocks5socketengine.cpp b/src/network/socket/qsocks5socketengine.cpp
index c365635..88b5aca 100644
--- a/src/network/socket/qsocks5socketengine.cpp
+++ b/src/network/socket/qsocks5socketengine.cpp
@@ -1540,8 +1540,13 @@ qint64 QSocks5SocketEngine::write(const char *data, qint64 len)
             // ### Handle this error.
         }
 
-        d->data->controlSocket->write(sealedBuf);
+        qint64 written = d->data->controlSocket->write(sealedBuf);
+        if (written <= 0) {
+            QSOCKS5_Q_DEBUG << "native write returned" << written;
+            return written;
+        }
         d->data->controlSocket->waitForBytesWritten(0);
+        //NB: returning len rather than written for the OK case, because the "sealing" may increase the length
         return len;
 #ifndef QT_NO_UDPSOCKET
     } else if (d->mode == QSocks5SocketEnginePrivate::UdpAssociateMode) {