237 lines
7.4 KiB
C++
237 lines
7.4 KiB
C++
/****************************************************************************
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**
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** Copyright (C) 2015 Konstantin Ritt <ritt.ks@gmail.com>
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** Copyright (C) 2016 The Qt Company Ltd.
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** Copyright (C) 2015 Klarälvdalens Datakonsult AB, a KDAB Group company, info@kdab.com, author Tobias Koenig <tobias.koenig@kdab.com>
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** Contact: https://www.qt.io/licensing/
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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 The Qt Company. For licensing terms
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** and conditions see https://www.qt.io/terms-conditions. For further
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** information use the contact form at https://www.qt.io/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 3 as published by the Free Software
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** Foundation and appearing in the file LICENSE.LGPL3 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 3 requirements
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** will be met: https://www.gnu.org/licenses/lgpl-3.0.html.
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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 2.0 or (at your option) the GNU General
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** Public license version 3 or any later version approved by the KDE Free
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** Qt Foundation. The licenses are as published by the Free Software
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** Foundation and appearing in the file LICENSE.GPL2 and LICENSE.GPL3
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** included in the packaging of this file. Please review the following
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** information to ensure the GNU General Public License requirements will
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** be met: https://www.gnu.org/licenses/gpl-2.0.html and
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** https://www.gnu.org/licenses/gpl-3.0.html.
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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 <qfile.h>
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#include <errno.h>
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#ifdef QT_POSIX_IPC
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#ifndef QT_NO_SHAREDMEMORY
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#include <sys/types.h>
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#include <sys/mman.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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#include "private/qcore_unix_p.h"
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QT_BEGIN_NAMESPACE
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int QSharedMemoryPrivate::handle()
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{
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// don't allow making handles on empty keys
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const QString safeKey = makePlatformSafeKey(key);
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if (safeKey.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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return 1;
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}
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bool QSharedMemoryPrivate::cleanHandle()
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{
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qt_safe_close(hand);
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hand = -1;
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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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if (!handle())
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return false;
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const QByteArray shmName = QFile::encodeName(makePlatformSafeKey(key));
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int fd;
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#ifdef O_CLOEXEC
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// First try with O_CLOEXEC flag, if that fails, fall back to normal flags
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EINTR_LOOP(fd, ::shm_open(shmName.constData(), O_RDWR | O_CREAT | O_EXCL | O_CLOEXEC, 0600));
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if (fd == -1)
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EINTR_LOOP(fd, ::shm_open(shmName.constData(), O_RDWR | O_CREAT | O_EXCL, 0600));
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#else
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EINTR_LOOP(fd, ::shm_open(shmName.constData(), O_RDWR | O_CREAT | O_EXCL, 0600));
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#endif
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if (fd == -1) {
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const int errorNumber = errno;
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const QLatin1String function("QSharedMemory::attach (shm_open)");
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switch (errorNumber) {
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case ENAMETOOLONG:
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case EINVAL:
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errorString = QSharedMemory::tr("%1: bad name").arg(function);
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error = QSharedMemory::KeyError;
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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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// the size may only be set once
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int ret;
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EINTR_LOOP(ret, QT_FTRUNCATE(fd, size));
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if (ret == -1) {
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setErrorString(QLatin1String("QSharedMemory::create (ftruncate)"));
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qt_safe_close(fd);
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return false;
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}
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qt_safe_close(fd);
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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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const QByteArray shmName = QFile::encodeName(makePlatformSafeKey(key));
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const int oflag = (mode == QSharedMemory::ReadOnly ? O_RDONLY : O_RDWR);
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const mode_t omode = (mode == QSharedMemory::ReadOnly ? 0400 : 0600);
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#ifdef O_CLOEXEC
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// First try with O_CLOEXEC flag, if that fails, fall back to normal flags
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EINTR_LOOP(hand, ::shm_open(shmName.constData(), oflag | O_CLOEXEC, omode));
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if (hand == -1)
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EINTR_LOOP(hand, ::shm_open(shmName.constData(), oflag, omode));
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#else
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EINTR_LOOP(hand, ::shm_open(shmName.constData(), oflag, omode));
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#endif
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if (hand == -1) {
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const int errorNumber = errno;
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const QLatin1String function("QSharedMemory::attach (shm_open)");
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switch (errorNumber) {
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case ENAMETOOLONG:
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case EINVAL:
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errorString = QSharedMemory::tr("%1: bad name").arg(function);
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error = QSharedMemory::KeyError;
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break;
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default:
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setErrorString(function);
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}
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hand = -1;
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return false;
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}
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// grab the size
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QT_STATBUF st;
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if (QT_FSTAT(hand, &st) == -1) {
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setErrorString(QLatin1String("QSharedMemory::attach (fstat)"));
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cleanHandle();
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return false;
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}
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size = st.st_size;
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// grab the memory
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const int mprot = (mode == QSharedMemory::ReadOnly ? PROT_READ : PROT_READ | PROT_WRITE);
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memory = QT_MMAP(0, size, mprot, MAP_SHARED, hand, 0);
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if (memory == MAP_FAILED || !memory) {
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setErrorString(QLatin1String("QSharedMemory::attach (mmap)"));
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cleanHandle();
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memory = 0;
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size = 0;
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return false;
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}
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#ifdef F_ADD_SEALS
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// Make sure the shared memory region will not shrink
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// otherwise someone could cause SIGBUS on us.
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// (see http://lwn.net/Articles/594919/)
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fcntl(hand, F_ADD_SEALS, F_SEAL_SHRINK);
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#endif
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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 (::munmap(memory, size) == -1) {
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setErrorString(QLatin1String("QSharedMemory::detach (munmap)"));
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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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#ifdef Q_OS_QNX
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// On QNX the st_nlink field of struct stat contains the number of
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// active shm_open() connections to the shared memory file, so we
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// can use it to automatically clean up the file once the last
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// user has detached from it.
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// get the number of current attachments
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int shm_nattch = 0;
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QT_STATBUF st;
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if (QT_FSTAT(hand, &st) == 0) {
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// subtract 2 from linkcount: one for our own open and one for the dir entry
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shm_nattch = st.st_nlink - 2;
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}
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cleanHandle();
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// if there are no attachments then unlink the shared memory
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if (shm_nattch == 0) {
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const QByteArray shmName = QFile::encodeName(makePlatformSafeKey(key));
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if (::shm_unlink(shmName.constData()) == -1 && errno != ENOENT)
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setErrorString(QLatin1String("QSharedMemory::detach (shm_unlink)"));
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}
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#else
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// On non-QNX systems (tested Linux and Haiku), the st_nlink field is always 1,
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// so we'll simply leak the shared memory files.
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cleanHandle();
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#endif
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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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#endif // QT_POSIX_IPC
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