mirror of https://github.com/qt/qtbase.git
240 lines
7.6 KiB
C++
240 lines
7.6 KiB
C++
/****************************************************************************
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**
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** Copyright (C) 2013 Digia Plc and/or its subsidiary(-ies).
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** Contact: http://www.qt-project.org/legal
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**
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** This file is part of the QtCore module of the Qt Toolkit.
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**
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** $QT_BEGIN_LICENSE:LGPL$
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** Commercial License Usage
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** Licensees holding valid commercial Qt licenses may use this file in
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** accordance with the commercial license agreement provided with the
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** Software or, alternatively, in accordance with the terms contained in
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** a written agreement between you and Digia. For licensing terms and
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** conditions see http://qt.digia.com/licensing. For further information
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** use the contact form at http://qt.digia.com/contact-us.
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**
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** GNU Lesser General Public License Usage
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** Alternatively, this file may be used under the terms of the GNU Lesser
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** General Public License version 2.1 as published by the Free Software
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** Foundation and appearing in the file LICENSE.LGPL included in the
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** packaging of this file. Please review the following information to
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** ensure the GNU Lesser General Public License version 2.1 requirements
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** will be met: http://www.gnu.org/licenses/old-licenses/lgpl-2.1.html.
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**
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** In addition, as a special exception, Digia gives you certain additional
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** rights. These rights are described in the Digia Qt LGPL Exception
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** version 1.1, included in the file LGPL_EXCEPTION.txt in this package.
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**
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** GNU General Public License Usage
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** Alternatively, this file may be used under the terms of the GNU
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** General Public License version 3.0 as published by the Free Software
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** Foundation and appearing in the file LICENSE.GPL included in the
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** packaging of this file. Please review the following information to
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** ensure the GNU General Public License version 3.0 requirements will be
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** met: http://www.gnu.org/copyleft/gpl.html.
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**
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**
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** $QT_END_LICENSE$
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**
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****************************************************************************/
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#include "qsystemsemaphore.h"
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#include "qsystemsemaphore_p.h"
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#include <qdebug.h>
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#include <qfile.h>
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#include <qcoreapplication.h>
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#ifndef QT_NO_SYSTEMSEMAPHORE
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#include <sys/types.h>
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#include <sys/ipc.h>
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#include <sys/sem.h>
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#include <fcntl.h>
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#include <errno.h>
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#include "private/qcore_unix_p.h"
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// OpenBSD 4.2 doesn't define EIDRM, see BUGS section:
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// http://www.openbsd.org/cgi-bin/man.cgi?query=semop&manpath=OpenBSD+4.2
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#if defined(Q_OS_OPENBSD) && !defined(EIDRM)
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#define EIDRM EINVAL
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#endif
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QT_BEGIN_NAMESPACE
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QSystemSemaphorePrivate::QSystemSemaphorePrivate() :
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semaphore(-1), createdFile(false),
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createdSemaphore(false), unix_key(-1), error(QSystemSemaphore::NoError)
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{
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}
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void QSystemSemaphorePrivate::setErrorString(const QString &function)
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{
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// EINVAL is handled in functions so they can give better error strings
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switch (errno) {
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case EPERM:
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case EACCES:
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errorString = QCoreApplication::translate("QSystemSemaphore", "%1: permission denied").arg(function);
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error = QSystemSemaphore::PermissionDenied;
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break;
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case EEXIST:
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errorString = QCoreApplication::translate("QSystemSemaphore", "%1: already exists").arg(function);
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error = QSystemSemaphore::AlreadyExists;
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break;
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case ENOENT:
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errorString = QCoreApplication::translate("QSystemSemaphore", "%1: does not exist").arg(function);
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error = QSystemSemaphore::NotFound;
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break;
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case ERANGE:
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case ENOSPC:
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errorString = QCoreApplication::translate("QSystemSemaphore", "%1: out of resources").arg(function);
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error = QSystemSemaphore::OutOfResources;
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break;
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default:
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errorString = QCoreApplication::translate("QSystemSemaphore", "%1: unknown error %2").arg(function).arg(errno);
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error = QSystemSemaphore::UnknownError;
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#if defined QSYSTEMSEMAPHORE_DEBUG
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qDebug() << errorString << "key" << key << "errno" << errno << EINVAL;
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#endif
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}
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}
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/*!
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\internal
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Setup unix_key
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*/
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key_t QSystemSemaphorePrivate::handle(QSystemSemaphore::AccessMode mode)
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{
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if (key.isEmpty()){
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errorString = QCoreApplication::tr("%1: key is empty", "QSystemSemaphore").arg(QLatin1String("QSystemSemaphore::handle:"));
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error = QSystemSemaphore::KeyError;
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return -1;
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}
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// ftok requires that an actual file exists somewhere
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if (-1 != unix_key)
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return unix_key;
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// Create the file needed for ftok
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int built = QSharedMemoryPrivate::createUnixKeyFile(fileName);
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if (-1 == built) {
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errorString = QCoreApplication::tr("%1: unable to make key", "QSystemSemaphore").arg(QLatin1String("QSystemSemaphore::handle:"));
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error = QSystemSemaphore::KeyError;
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return -1;
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}
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createdFile = (1 == built);
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// Get the unix key for the created file
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unix_key = ftok(QFile::encodeName(fileName).constData(), 'Q');
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if (-1 == unix_key) {
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errorString = QCoreApplication::tr("%1: ftok failed", "QSystemSemaphore").arg(QLatin1String("QSystemSemaphore::handle:"));
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error = QSystemSemaphore::KeyError;
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return -1;
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}
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// Get semaphore
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semaphore = semget(unix_key, 1, 0600 | IPC_CREAT | IPC_EXCL);
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if (-1 == semaphore) {
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if (errno == EEXIST)
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semaphore = semget(unix_key, 1, 0600 | IPC_CREAT);
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if (-1 == semaphore) {
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setErrorString(QLatin1String("QSystemSemaphore::handle"));
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cleanHandle();
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return -1;
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}
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} else {
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createdSemaphore = true;
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// Force cleanup of file, it is possible that it can be left over from a crash
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createdFile = true;
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}
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if (mode == QSystemSemaphore::Create) {
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createdSemaphore = true;
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createdFile = true;
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}
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// Created semaphore so initialize its value.
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if (createdSemaphore && initialValue >= 0) {
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qt_semun init_op;
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init_op.val = initialValue;
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if (-1 == semctl(semaphore, 0, SETVAL, init_op)) {
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setErrorString(QLatin1String("QSystemSemaphore::handle"));
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cleanHandle();
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return -1;
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}
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}
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return unix_key;
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}
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/*!
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\internal
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Cleanup the unix_key
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*/
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void QSystemSemaphorePrivate::cleanHandle()
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{
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unix_key = -1;
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// remove the file if we made it
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if (createdFile) {
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QFile::remove(fileName);
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createdFile = false;
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}
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if (createdSemaphore) {
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if (-1 != semaphore) {
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if (-1 == semctl(semaphore, 0, IPC_RMID, 0)) {
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setErrorString(QLatin1String("QSystemSemaphore::cleanHandle"));
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#if defined QSYSTEMSEMAPHORE_DEBUG
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qDebug() << QLatin1String("QSystemSemaphore::cleanHandle semctl failed.");
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#endif
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}
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semaphore = -1;
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}
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createdSemaphore = false;
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}
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}
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/*!
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\internal
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*/
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bool QSystemSemaphorePrivate::modifySemaphore(int count)
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{
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if (-1 == handle())
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return false;
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struct sembuf operation;
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operation.sem_num = 0;
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operation.sem_op = count;
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operation.sem_flg = SEM_UNDO;
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int res;
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EINTR_LOOP(res, semop(semaphore, &operation, 1));
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if (-1 == res) {
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// If the semaphore was removed be nice and create it and then modifySemaphore again
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if (errno == EINVAL || errno == EIDRM) {
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semaphore = -1;
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cleanHandle();
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handle();
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return modifySemaphore(count);
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}
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setErrorString(QLatin1String("QSystemSemaphore::modifySemaphore"));
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#if defined QSYSTEMSEMAPHORE_DEBUG
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qDebug() << QLatin1String("QSystemSemaphore::modify failed") << count << semctl(semaphore, 0, GETVAL) << errno << EIDRM << EINVAL;
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#endif
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return false;
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}
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clearError();
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return true;
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}
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QT_END_NAMESPACE
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#endif // QT_NO_SYSTEMSEMAPHORE
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