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/****************************************************************************
**
** Copyright (C) 2009 Nokia Corporation and/or its subsidiary(-ies).
** Contact: Nokia Corporation (qt-info@nokia.com)
**
** This file is part of the test suite 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 either Technology Preview License Agreement or the
** Beta Release License Agreement.
**
** 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 1.0, included in the file LGPL_EXCEPTION.txt in this
** package.
**
** GNU General Public License Usage
** Alternatively, this file may be used under the terms of the GNU
** General Public License version 3.0 as published by the Free Software
** Foundation and appearing in the file LICENSE.GPL included in the
** packaging of this file. Please review the following information to
** ensure the GNU General Public License version 3.0 requirements will be
** met: http://www.gnu.org/copyleft/gpl.html.
**
** If you are unsure which license is appropriate for your use, please
** contact the sales department at http://www.qtsoftware.com/contact.
** $QT_END_LICENSE$
**
****************************************************************************/
#include "qsystemlock.h"
#include "qsystemlock_p.h"
#include <qdebug.h>
#include <qfile.h>
#include <sys/types.h>
#include <sys/ipc.h>
#include <fcntl.h>
#include <errno.h>
#include <sys/shm.h>
#include <sys/sem.h>
// We have to define this as on some sem.h will have it
union qt_semun {
int val; /* value for SETVAL */
struct semid_ds *buf; /* buffer for IPC_STAT, IPC_SET */
unsigned short *array; /* array for GETALL, SETALL */
};
#define tr(x) QT_TRANSLATE_NOOP(QLatin1String("QSystemLock"), (x))
QSystemLockPrivate::QSystemLockPrivate() :
semaphore(-1), lockCount(0),
error(QSystemLock::NoError), unix_key(-1), createdFile(false), createdSemaphore(false)
{
}
void QSystemLockPrivate::setErrorString(const QString &function)
{
switch (errno) {
case EIDRM:
errorString = function + QLatin1String(": ") + tr("The semaphore set was removed");
error = QSystemLock::UnknownError;
break;
default:
errorString = function + QLatin1String(": ") + tr("unknown error");
error = QSystemLock::UnknownError;
qWarning() << errorString << "key" << key << "errno" << errno << ERANGE << ENOMEM << EINVAL << EINTR << EFBIG << EFAULT << EAGAIN << EACCES << E2BIG;
}
}
/*!
\internal
Setup unix_key
*/
key_t QSystemLockPrivate::handle()
{
if (key.isEmpty())
return -1;
// ftok requires that an actual file exists somewhere
// If we have already made at some point in the past,
// double check that it is still there.
if (-1 != unix_key) {
int aNewunix_key = ftok(QFile::encodeName(fileName).constData(), 'Q');
if (aNewunix_key != unix_key) {
cleanHandle();
} else {
return unix_key;
}
}
// Create the file needed for ftok
int built = QSharedMemoryPrivate::createUnixKeyFile(fileName);
if (-1 == built)
return -1;
createdFile = (1 == built);
// Get the unix key for the created file
unix_key = ftok(QFile::encodeName(fileName).constData(), 'Q');
if (-1 == unix_key) {
setErrorString(QLatin1String("QSystemLock::handle ftok"));
return -1;
}
// Get semaphore
semaphore = semget(unix_key, 1, 0666 | IPC_CREAT | IPC_EXCL);
if (-1 == semaphore) {
if (errno == EEXIST)
semaphore = semget(unix_key, 1, 0666 | IPC_CREAT);
if (-1 == semaphore) {
setErrorString(QLatin1String("QSystemLock::handle semget"));
cleanHandle();
return -1;
}
} else {
// Created semaphore, initialize value.
createdSemaphore = true;
qt_semun init_op;
init_op.val = MAX_LOCKS;
if (-1 == semctl(semaphore, 0, SETVAL, init_op)) {
setErrorString(QLatin1String("QSystemLock::handle semctl"));
cleanHandle();
return -1;
}
}
return unix_key;
}
/*!
\internal
Cleanup the unix_key
*/
void QSystemLockPrivate::cleanHandle()
{
unix_key = -1;
// remove the file if we made it
if (createdFile) {
if (!QFile::remove(fileName))
setErrorString(QLatin1String("QSystemLock::cleanHandle QFile::remove"));
createdFile = false;
}
if (createdSemaphore) {
if (-1 != semaphore) {
if (-1 == semctl(semaphore, 0, IPC_RMID)) {
setErrorString(QLatin1String("QSystemLock::cleanHandle semctl"));
}
semaphore = -1;
}
createdSemaphore = false;
}
}
/*!
\internal
modifySemaphore generates operation.sem_op and handles recursive behavior.
*/
bool QSystemLockPrivate::modifySemaphore(QSystemLockPrivate::Operation op,
QSystemLock::LockMode mode)
{
if (-1 == handle())
return false;
if ((lockCount == 0 && op == Lock) || (lockCount > 0 && op == Unlock)) {
if (op == Unlock) {
--lockCount;
Q_ASSERT(lockCount >= 0);
if (lockCount > 0)
return true;
}
struct sembuf operation;
operation.sem_num = 0;
operation.sem_op = (mode == QSystemLock::ReadWrite) ? MAX_LOCKS : 1;
if (op == Lock)
operation.sem_op *= -1;
operation.sem_flg = SEM_UNDO;
if (-1 == semop(semaphore, &operation, 1)) {
setErrorString(QLatin1String("QSystemLock::modify"));
return false;
}
lockedMode = mode;
}
if (op == Lock)
lockCount++;
return true;
}
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