source: trunk/tools/qvfb/qlock.cpp@ 855

/****************************************************************************
**
** Copyright (C) 2011 Nokia Corporation and/or its subsidiary(-ies).
** All rights reserved.
** Contact: Nokia Corporation ([email protected])
**
** This file is part of the QtGui module of the Qt Toolkit.
**
** $QT_BEGIN_LICENSE:LGPL$
** Commercial Usage
** Licensees holding valid Qt Commercial licenses may use this file in
** accordance with the Qt Commercial License Agreement provided with the
** Software or, alternatively, in accordance with the terms contained in
** a written agreement between you and Nokia.
**
** 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.
**
** 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 have questions regarding the use of this file, please contact
** Nokia at [email protected].
** $QT_END_LICENSE$
**
****************************************************************************/

#include "qlock_p.h"


#ifdef QT_NO_QWS_MULTIPROCESS

QT_BEGIN_NAMESPACE

/* no multiprocess - use a dummy */

QLock::QLock(const QString & /*filename*/, char /*id*/, bool /*create*/)
    : type(Read), data(0)
{
}

QLock::~QLock()
{
}

bool QLock::isValid() const
{
    return true;
}

void QLock::lock(Type t)
{
    data = (QLockData *)-1;
    type = t;
}

void QLock::unlock()
{
    data = 0;
}

bool QLock::locked() const
{
    return data;
}

QT_END_NAMESPACE

#else // QT_NO_QWS_MULTIPROCESS

#include "qwssignalhandler_p.h"

#include <unistd.h>
#include <sys/types.h>
#if defined(Q_OS_DARWIN)
#   define Q_NO_SEMAPHORE
#   include <sys/stat.h>
#   include <sys/file.h>
#else // Q_OS_DARWIN
#   include <sys/sem.h>
#   if (defined(__GNU_LIBRARY__) && !defined(_SEM_SEMUN_UNDEFINED) && !defined(QT_LINUXBASE)) \
    || defined(Q_OS_FREEBSD) || defined(Q_OS_OPENBSD) || defined(Q_OS_NETBSD) \
    || defined(Q_OS_BSDI)
        /* union semun is defined by including <sys/sem.h> */
#   else
/* according to X/OPEN we have to define it ourselves */
union semun {
    int val;                    /* value for SETVAL */
    struct semid_ds *buf;       /* buffer for IPC_STAT, IPC_SET */
    unsigned short *array;      /* array for GETALL, SETALL */
};
#   endif
#endif // Q_OS_DARWIN
#include <sys/ipc.h>
#include <string.h>
#include <errno.h>
#include <qdebug.h>
#include <signal.h>

#include <private/qcore_unix_p.h> // overrides QT_OPEN


QT_BEGIN_NAMESPACE

#define MAX_LOCKS   200            // maximum simultaneous read locks

class QLockData
{
public:
#ifdef Q_NO_SEMAPHORE
    QByteArray file;
#endif // Q_NO_SEMAPHORE
    int id;
    int count;
    bool owned;
};

/*!
    \class QLock
    \brief The QLock class is a wrapper for a System V shared semaphore.

    \ingroup qws

    \internal

    It is used by \l{Qt for Embedded Linux} for synchronizing access to the graphics
    card and shared memory region between processes.
*/

/*!
    \enum QLock::Type

    \value Read
    \value Write
*/

/*!
    \fn QLock::QLock(const QString &filename, char id, bool create)

    Creates a lock. \a filename is the file path of the Unix-domain
    socket the \l{Qt for Embedded Linux} client is using. \a id is the name of the
    particular lock to be created on that socket. If \a create is true
    the lock is to be created (as the Qt for Embedded Linux server does); if \a
    create is false the lock should exist already (as the Qt for Embedded Linux
    client expects).
*/

QLock::QLock(const QString &filename, char id, bool create)
{
    data = new QLockData;
    data->count = 0;
#ifdef Q_NO_SEMAPHORE
    data->file = QString(filename+id).toLocal8Bit().constData();
    for(int x = 0; x < 2; x++) {
        data->id = QT_OPEN(data->file, O_RDWR | (x ? O_CREAT : 0), S_IRWXU);
        if(data->id != -1 || !create) {
            data->owned = x;
            break;
        }
    }
#else
    key_t semkey = ftok(filename.toLocal8Bit().constData(), id);
    data->id = semget(semkey,0,0);
    data->owned = create;
    if (create) {
        semun arg; arg.val = 0;