QLocalSocket: forward skipping to the inner socket

As QLocalSocket keeps incoming data in the inner socket object, we
can implement the outer's skip() by simply calling the inner's. This
avoids the slow read()-based code path provided by the base class.

Change-Id: I66547601ebad1b4acf168475bebd81fbeef969f8
Reviewed-by: Timur Pocheptsov <timur.pocheptsov@qt.io>
Reviewed-by: Edward Welbourne <edward.welbourne@qt.io>

src/network/socket/qlocalsocket_p.h

@@ -120,6 +120,7 @@ public:
     void init();
 
 #if defined(QT_LOCALSOCKET_TCP)
+    qint64 skip(qint64 maxSize) override;
     QLocalUnixSocket* tcpSocket;
     bool ownsTcpSocket;
     void setSocket(QLocalUnixSocket*);
@@ -139,6 +140,7 @@ public:
     QWindowsPipeReader *pipeReader;
     QLocalSocket::LocalSocketError error;
 #else
+    qint64 skip(qint64 maxSize) override;
     QLocalUnixSocket unixSocket;
     QString generateErrorString(QLocalSocket::LocalSocketError, const QString &function) const;
     void errorOccurred(QLocalSocket::LocalSocketError, const QString &function);

src/network/socket/qlocalsocket_tcp.cpp

@@ -83,6 +83,11 @@ void QLocalSocketPrivate::setSocket(QLocalUnixSocket* socket)
     tcpSocket->setParent(q);
 }
 
+qint64 QLocalSocketPrivate::skip(qint64 maxSize)
+{
+    return tcpSocket->skip(maxSize);
+}
+
 void QLocalSocketPrivate::_q_error(QAbstractSocket::SocketError socketError)
 {
     Q_Q(QLocalSocket);

src/network/socket/qlocalsocket_unix.cpp

@@ -88,6 +88,11 @@ void QLocalSocketPrivate::init()
     unixSocket.setParent(q);
 }
 
+qint64 QLocalSocketPrivate::skip(qint64 maxSize)
+{
+    return unixSocket.skip(maxSize);
+}
+
 void QLocalSocketPrivate::_q_error(QAbstractSocket::SocketError socketError)
 {
     Q_Q(QLocalSocket);