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/****************************************************************************
**
** Copyright (C) 2010 Nokia Corporation and/or its subsidiary(-ies).
** All rights reserved.
** Contact: Nokia Corporation (qt-info@nokia.com)
**
** This file is part of the QtCore module of the Qt Toolkit.
**
** $QT_BEGIN_LICENSE:LGPL$
** No Commercial Usage
** This file contains pre-release code and may not be distributed.
** You may use this file in accordance with the terms and conditions
** contained in the Technology Preview License Agreement accompanying
** this package.
**
** GNU Lesser General Public License Usage
** Alternatively, this file may be used under the terms of the GNU Lesser
** General Public License version 2.1 as published by the Free Software
** Foundation and appearing in the file LICENSE.LGPL included in the
** packaging of this file. Please review the following information to
** ensure the GNU Lesser General Public License version 2.1 requirements
** will be met: http://www.gnu.org/licenses/old-licenses/lgpl-2.1.html.
**
** In addition, as a special exception, Nokia gives you certain additional
** rights. These rights are described in the Nokia Qt LGPL Exception
** version 1.1, included in the file LGPL_EXCEPTION.txt in this package.
**
** If you have questions regarding the use of this file, please contact
** Nokia at qt-info@nokia.com.
**
**
**
**
**
**
**
**
** $QT_END_LICENSE$
**
****************************************************************************/
#include "qcore_unix_p.h"
#include "qelapsedtimer.h"
#ifndef Q_OS_VXWORKS
# if !defined(Q_OS_HPUX) || defined(__ia64)
# include <sys/select.h>
# endif
# include <sys/time.h>
#else
# include <selectLib.h>
#endif
#include <stdlib.h>
#ifdef Q_OS_MAC
#include <mach/mach_time.h>
#endif
QT_BEGIN_NAMESPACE
static inline bool time_update(struct timeval *tv, const struct timeval &start,
const struct timeval &timeout)
{
if (!QElapsedTimer::isMonotonic()) {
// we cannot recalculate the timeout without a monotonic clock as the time may have changed
return false;
}
// clock source is monotonic, so we can recalculate how much timeout is left
struct timeval now = qt_gettime();
*tv = timeout + start - now;
return tv->tv_sec >= 0;
}
int qt_safe_select(int nfds, fd_set *fdread, fd_set *fdwrite, fd_set *fdexcept,
const struct timeval *orig_timeout)
{
if (!orig_timeout) {
// no timeout -> block forever
register int ret;
EINTR_LOOP(ret, select(nfds, fdread, fdwrite, fdexcept, 0));
return ret;
}
timeval start = qt_gettime();
timeval timeout = *orig_timeout;
// loop and recalculate the timeout as needed
int ret;
forever {
ret = ::select(nfds, fdread, fdwrite, fdexcept, &timeout);
if (ret != -1 || errno != EINTR)
return ret;
// recalculate the timeout
if (!time_update(&timeout, start, *orig_timeout)) {
// timeout during update
// or clock reset, fake timeout error
return 0;
}
}
}
QT_END_NAMESPACE
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