299 lines
8.7 KiB
C++
299 lines
8.7 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 "qplatformdefs.h"
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#include "qsharedmemory.h"
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#include "qsharedmemory_p.h"
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#include "qsystemsemaphore.h"
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#include <qdir.h>
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#include <qdebug.h>
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#include <errno.h>
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#ifndef QT_NO_SHAREDMEMORY
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#include <sys/types.h>
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#include <sys/ipc.h>
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#include <sys/shm.h>
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#include <sys/stat.h>
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#include <fcntl.h>
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#include <unistd.h>
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#endif //QT_NO_SHAREDMEMORY
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#include "private/qcore_unix_p.h"
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#ifndef QT_NO_SHAREDMEMORY
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QT_BEGIN_NAMESPACE
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QSharedMemoryPrivate::QSharedMemoryPrivate()
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: QObjectPrivate(), memory(0), size(0), error(QSharedMemory::NoError),
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#ifndef QT_NO_SYSTEMSEMAPHORE
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systemSemaphore(QString()), lockedByMe(false),
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#endif
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unix_key(0)
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{
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}
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void QSharedMemoryPrivate::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 EACCES:
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errorString = QSharedMemory::tr("%1: permission denied").arg(function);
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error = QSharedMemory::PermissionDenied;
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break;
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case EEXIST:
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errorString = QSharedMemory::tr("%1: already exists").arg(function);
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error = QSharedMemory::AlreadyExists;
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break;
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case ENOENT:
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errorString = QSharedMemory::tr("%1: doesn't exist").arg(function);
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error = QSharedMemory::NotFound;
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break;
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case EMFILE:
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case ENOMEM:
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case ENOSPC:
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errorString = QSharedMemory::tr("%1: out of resources").arg(function);
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error = QSharedMemory::OutOfResources;
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break;
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default:
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errorString = QSharedMemory::tr("%1: unknown error %2").arg(function).arg(errno);
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error = QSharedMemory::UnknownError;
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#if defined QSHAREDMEMORY_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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If not already made create the handle used for accessing the shared memory.
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*/
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key_t QSharedMemoryPrivate::handle()
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{
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// already made
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if (unix_key)
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return unix_key;
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// don't allow making handles on empty keys
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if (nativeKey.isEmpty()) {
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errorString = QSharedMemory::tr("%1: key is empty").arg(QLatin1String("QSharedMemory::handle:"));
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error = QSharedMemory::KeyError;
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return 0;
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}
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// ftok requires that an actual file exists somewhere
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if (!QFile::exists(nativeKey)) {
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errorString = QSharedMemory::tr("%1: UNIX key file doesn't exist").arg(QLatin1String("QSharedMemory::handle:"));
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error = QSharedMemory::NotFound;
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return 0;
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}
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unix_key = ftok(QFile::encodeName(nativeKey).constData(), 'Q');
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if (-1 == unix_key) {
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errorString = QSharedMemory::tr("%1: ftok failed").arg(QLatin1String("QSharedMemory::handle:"));
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error = QSharedMemory::KeyError;
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unix_key = 0;
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}
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return unix_key;
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}
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#endif // QT_NO_SHAREDMEMORY
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#if !(defined(QT_NO_SHAREDMEMORY) && defined(QT_NO_SYSTEMSEMAPHORE))
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/*!
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\internal
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Creates the unix file if needed.
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returns \c true if the unix file was created.
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-1 error
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0 already existed
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1 created
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*/
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int QSharedMemoryPrivate::createUnixKeyFile(const QString &fileName)
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{
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int fd = qt_safe_open(QFile::encodeName(fileName).constData(),
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O_EXCL | O_CREAT | O_RDWR, 0640);
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if (-1 == fd) {
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if (errno == EEXIST)
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return 0;
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return -1;
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} else {
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close(fd);
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}
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return 1;
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}
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#endif // QT_NO_SHAREDMEMORY && QT_NO_SYSTEMSEMAPHORE
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#ifndef QT_NO_SHAREDMEMORY
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bool QSharedMemoryPrivate::cleanHandle()
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{
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unix_key = 0;
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return true;
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}
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bool QSharedMemoryPrivate::create(int size)
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{
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// build file if needed
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bool createdFile = false;
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int built = createUnixKeyFile(nativeKey);
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if (built == -1) {
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errorString = QSharedMemory::tr("%1: unable to make key").arg(QLatin1String("QSharedMemory::handle:"));
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error = QSharedMemory::KeyError;
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return false;
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}
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if (built == 1) {
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createdFile = true;
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}
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// get handle
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if (!handle()) {
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if (createdFile)
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QFile::remove(nativeKey);
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return false;
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}
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// create
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if (-1 == shmget(unix_key, size, 0600 | IPC_CREAT | IPC_EXCL)) {
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QString function = QLatin1String("QSharedMemory::create");
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switch (errno) {
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case EINVAL:
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errorString = QSharedMemory::tr("%1: system-imposed size restrictions").arg(QLatin1String("QSharedMemory::handle"));
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error = QSharedMemory::InvalidSize;
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break;
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default:
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setErrorString(function);
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}
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if (createdFile && error != QSharedMemory::AlreadyExists)
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QFile::remove(nativeKey);
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return false;
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}
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return true;
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}
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bool QSharedMemoryPrivate::attach(QSharedMemory::AccessMode mode)
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{
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// grab the shared memory segment id
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int id = shmget(unix_key, 0, (mode == QSharedMemory::ReadOnly ? 0400 : 0600));
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if (-1 == id) {
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setErrorString(QLatin1String("QSharedMemory::attach (shmget)"));
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return false;
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}
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// grab the memory
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memory = shmat(id, 0, (mode == QSharedMemory::ReadOnly ? SHM_RDONLY : 0));
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if ((void*) - 1 == memory) {
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memory = 0;
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setErrorString(QLatin1String("QSharedMemory::attach (shmat)"));
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return false;
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}
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// grab the size
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shmid_ds shmid_ds;
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if (!shmctl(id, IPC_STAT, &shmid_ds)) {
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size = (int)shmid_ds.shm_segsz;
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} else {
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setErrorString(QLatin1String("QSharedMemory::attach (shmctl)"));
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return false;
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}
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return true;
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}
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bool QSharedMemoryPrivate::detach()
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{
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// detach from the memory segment
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if (-1 == shmdt(memory)) {
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QString function = QLatin1String("QSharedMemory::detach");
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switch (errno) {
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case EINVAL:
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errorString = QSharedMemory::tr("%1: not attached").arg(function);
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error = QSharedMemory::NotFound;
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break;
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default:
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setErrorString(function);
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}
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return false;
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}
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memory = 0;
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size = 0;
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// Get the number of current attachments
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int id = shmget(unix_key, 0, 0400);
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cleanHandle();
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struct shmid_ds shmid_ds;
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if (0 != shmctl(id, IPC_STAT, &shmid_ds)) {
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switch (errno) {
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case EINVAL:
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return true;
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default:
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return false;
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}
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}
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// If there are no attachments then remove it.
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if (shmid_ds.shm_nattch == 0) {
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// mark for removal
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if (-1 == shmctl(id, IPC_RMID, &shmid_ds)) {
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setErrorString(QLatin1String("QSharedMemory::remove"));
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switch (errno) {
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case EINVAL:
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return true;
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default:
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return false;
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}
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}
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// remove file
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if (!QFile::remove(nativeKey))
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return false;
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}
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return true;
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}
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QT_END_NAMESPACE
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#endif // QT_NO_SHAREDMEMORY
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