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266 lines
8.4 KiB
266 lines
8.4 KiB
/****************************************************************************
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**
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** Implementation of QSocketNotifier class
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**
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** Created : 951114
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**
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** Copyright (C) 1992-2008 Trolltech ASA. All rights reserved.
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**
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** This file is part of the kernel module of the Qt GUI Toolkit.
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**
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** This file may be used under the terms of the GNU General
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** Public License versions 2.0 or 3.0 as published by the Free
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** Software Foundation and appearing in the files LICENSE.GPL2
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** and LICENSE.GPL3 included in the packaging of this file.
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** Alternatively you may (at your option) use any later version
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** of the GNU General Public License if such license has been
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** publicly approved by Trolltech ASA (or its successors, if any)
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** and the KDE Free Qt Foundation.
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**
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** Please review the following information to ensure GNU General
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** Public Licensing requirements will be met:
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** http://trolltech.com/products/qt/licenses/licensing/opensource/.
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** If you are unsure which license is appropriate for your use, please
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** review the following information:
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** http://trolltech.com/products/qt/licenses/licensing/licensingoverview
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** or contact the sales department at sales@trolltech.com.
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**
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** This file may be used under the terms of the Q Public License as
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** defined by Trolltech ASA and appearing in the file LICENSE.QPL
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** included in the packaging of this file. Licensees holding valid Qt
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** Commercial licenses may use this file in accordance with the Qt
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** Commercial License Agreement provided with the Software.
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**
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** This file is provided "AS IS" with NO WARRANTY OF ANY KIND,
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** INCLUDING THE WARRANTIES OF DESIGN, MERCHANTABILITY AND FITNESS FOR
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** A PARTICULAR PURPOSE. Trolltech reserves all rights not granted
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** herein.
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**
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**********************************************************************/
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#include "qsocketnotifier.h"
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#include "qapplication.h"
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#include "qevent.h"
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#include "qeventloop.h"
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#include "qplatformdefs.h"
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#if defined(Q_OS_UNIX)
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#include <sys/types.h>
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#endif
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/*!
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\class QSocketNotifier qsocketnotifier.h
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\brief The QSocketNotifier class provides support for socket callbacks.
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\ingroup io
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This class makes it possible to write asynchronous socket-based
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code in Qt. Using synchronous socket operations blocks the
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program, which is clearly not acceptable for an event-driven GUI
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program.
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Once you have opened a non-blocking socket (whether for TCP, UDP,
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a UNIX-domain socket, or any other protocol family your operating
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system supports), you can create a socket notifier to monitor the
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socket. Then you connect the activated() signal to the slot you
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want to be called when a socket event occurs.
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Note for Windows users: the socket passed to QSocketNotifier will
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become non-blocking, even if it was created as a blocking socket.
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There are three types of socket notifiers (read, write and
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exception); you must specify one of these in the constructor.
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The type specifies when the activated() signal is to be emitted:
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\list 1
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\i QSocketNotifier::Read - There is data to be read (socket read event).
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\i QSocketNotifier::Write - Data can be written (socket write event).
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\i QSocketNofifier::Exception - An exception has occurred (socket
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exception event). We recommend against using this.
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\endlist
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For example, if you need to monitor both reads and writes for the
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same socket you must create two socket notifiers.
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For read notifiers it makes little sense to connect the
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activated() signal to more than one slot because the data can be
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read from the socket only once.
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Also observe that if you do not read all the available data when
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the read notifier fires, it fires again and again.
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For write notifiers, immediately disable the notifier after the
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activated() signal has been received and you have sent the data to
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be written on the socket. When you have more data to be written,
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enable it again to get a new activated() signal. The exception is
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if the socket data writing operation (send() or equivalent) fails
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with a "would block" error, which means that some buffer is full
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and you must wait before sending more data. In that case you do
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not need to disable and re-enable the write notifier; it will fire
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again as soon as the system allows more data to be sent.
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The behavior of a write notifier that is left in enabled state
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after having emitting the first activated() signal (and no "would
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block" error has occurred) is undefined. Depending on the
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operating system, it may fire on every pass of the event loop or
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not at all.
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If you need a time-out for your sockets you can use either \link
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QObject::startTimer() timer events\endlink or the QTimer class.
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Socket action is detected in the \link QApplication::exec() main
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event loop\endlink of Qt. The X11 version of Qt has a single UNIX
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select() call that incorporates all socket notifiers and the X
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socket.
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Note that on XFree86 for OS/2, select() works only in the thread
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in which main() is running; you should therefore use that thread
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for GUI operations.
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\sa QSocket, QServerSocket, QSocketDevice, QFile::handle()
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*/
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/*!
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\enum QSocketNotifier::Type
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\value Read
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\value Write
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\value Exception
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*/
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/*!
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Constructs a socket notifier called \a name, with the parent, \a
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parent. It watches \a socket for \a type events, and enables it.
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It is generally advisable to explicitly enable or disable the
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socket notifier, especially for write notifiers.
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\sa setEnabled(), isEnabled()
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*/
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QSocketNotifier::QSocketNotifier( int socket, Type type, QObject *parent,
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const char *name )
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: QObject( parent, name )
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{
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#if defined(QT_CHECK_RANGE)
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if ( socket < 0 )
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qWarning( "QSocketNotifier: Invalid socket specified" );
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# if defined(Q_OS_UNIX)
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if ( socket >= FD_SETSIZE )
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qWarning( "QSocketNotifier: Socket descriptor too large for select()" );
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# endif
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#endif
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sockfd = socket;
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sntype = type;
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snenabled = TRUE;
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QApplication::eventLoop()->registerSocketNotifier( this );
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}
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/*!
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Destroys the socket notifier.
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*/
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QSocketNotifier::~QSocketNotifier()
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{
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setEnabled( FALSE );
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}
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/*!
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\fn void QSocketNotifier::activated( int socket )
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This signal is emitted under certain conditions specified by the
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notifier type():
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\list 1
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\i QSocketNotifier::Read - There is data to be read (socket read event).
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\i QSocketNotifier::Write - Data can be written (socket write event).
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\i QSocketNofifier::Exception - An exception has occurred (socket
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exception event).
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\endlist
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The \a socket argument is the \link socket() socket\endlink identifier.
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\sa type(), socket()
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*/
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/*!
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\fn int QSocketNotifier::socket() const
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Returns the socket identifier specified to the constructor.
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\sa type()
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*/
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/*!
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\fn Type QSocketNotifier::type() const
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Returns the socket event type specified to the constructor: \c
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QSocketNotifier::Read, \c QSocketNotifier::Write, or \c
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QSocketNotifier::Exception.
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\sa socket()
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*/
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/*!
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\fn bool QSocketNotifier::isEnabled() const
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Returns TRUE if the notifier is enabled; otherwise returns FALSE.
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\sa setEnabled()
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*/
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/*!
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Enables the notifier if \a enable is TRUE or disables it if \a
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enable is FALSE.
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The notifier is enabled by default.
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If the notifier is enabled, it emits the activated() signal
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whenever a socket event corresponding to its \link type()
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type\endlink occurs. If it is disabled, it ignores socket events
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(the same effect as not creating the socket notifier).
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Write notifiers should normally be disabled immediately after the
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activated() signal has been emitted; see discussion of write
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notifiers in the \link #details class description\endlink above.
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\sa isEnabled(), activated()
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*/
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void QSocketNotifier::setEnabled( bool enable )
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{
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if ( sockfd < 0 )
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return;
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if ( snenabled == enable ) // no change
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return;
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snenabled = enable;
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QEventLoop *eventloop = QApplication::eventLoop();
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if ( ! eventloop ) // perhaps application is shutting down
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return;
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if ( snenabled )
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eventloop->registerSocketNotifier( this );
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else
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eventloop->unregisterSocketNotifier( this );
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}
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/*!\reimp
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*/
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bool QSocketNotifier::event( QEvent *e )
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{
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// Emits the activated() signal when a \c QEvent::SockAct is
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// received.
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QObject::event( e ); // will activate filters
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if ( e->type() == QEvent::SockAct ) {
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emit activated( sockfd );
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return TRUE;
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}
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return FALSE;
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}
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