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+/****************************************************************************
+**
+** Copyright (C) 2011 Nokia Corporation and/or its subsidiary(-ies).
+** All rights reserved.
+** Contact: Nokia Corporation (qt-info@nokia.com)
+**
+** This file is part of the QtGui module 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 Technology Preview License Agreement accompanying
+** this package.
+**
+** 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.
+**
+** If you have questions regarding the use of this file, please contact
+** Nokia at qt-info@nokia.com.
+**
+**
+**
+**
+**
+**
+**
+**
+** $QT_END_LICENSE$
+**
+****************************************************************************/
+
+#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
+
+#if defined(Q_OS_DARWIN)
+# define Q_NO_SEMAPHORE
+#endif
+
+#include "qwssignalhandler_p.h"
+
+#include <unistd.h>
+#include <sys/types.h>
+#include <sys/ipc.h>
+#if defined(Q_NO_SEMAPHORE)
+# include <sys/stat.h>
+# include <sys/file.h>
+#else
+# include <sys/sem.h>
+#endif
+#include <string.h>
+#include <errno.h>
+#include <qdebug.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) {
+ qt_semun arg; arg.val = 0;
+ if (data->id != -1)
+ semctl(data->id,0,IPC_RMID,arg);
+ data->id = semget(semkey,1,IPC_CREAT|0600);
+ arg.val = MAX_LOCKS;
+ semctl(data->id,0,SETVAL,arg);
+
+ QWSSignalHandler::instance()->addSemaphore(data->id);
+ }
+#endif
+ if (data->id == -1) {
+ int eno = errno;
+ qWarning("Cannot %s semaphore %s '%c'", (create ? "create" : "get"),
+ qPrintable(filename), id);
+ qDebug() << "Error" << eno << strerror(eno);
+ }
+}
+
+/*!
+ \fn QLock::~QLock()
+
+ Destroys a lock
+*/
+
+QLock::~QLock()
+{
+ if (locked())
+ unlock();
+#ifdef Q_NO_SEMAPHORE
+ if(isValid()) {
+ QT_CLOSE(data->id);
+ if(data->owned)
+ unlink(data->file);
+ }
+#else
+ if(data->owned)
+ QWSSignalHandler::instance()->removeSemaphore(data->id);
+#endif
+ delete data;
+}
+
+/*!
+ \fn bool QLock::isValid() const
+
+ Returns true if the lock constructor was successful; returns false if
+ the lock could not be created or was not available to connect to.
+*/
+
+bool QLock::isValid() const
+{
+ return (data->id != -1);
+}
+
+/*!
+ Locks the semaphore with a lock of type \a t. Locks can either be
+ \c Read or \c Write. If a lock is \c Read, attempts by other
+ processes to obtain \c Read locks will succeed, and \c Write
+ attempts will block until the lock is unlocked. If locked as \c
+ Write, all attempts to lock by other processes will block until
+ the lock is unlocked. Locks are stacked: i.e. a given QLock can be
+ locked multiple times by the same process without blocking, and
+ will only be unlocked after a corresponding number of unlock()
+ calls.
+*/
+
+void QLock::lock(Type t)
+{
+ if (!data->count) {
+#ifdef Q_NO_SEMAPHORE
+ int op = LOCK_SH;
+ if(t == Write)
+ op = LOCK_EX;
+ for(int rv=1; rv;) {
+ rv = flock(data->id, op);
+ if (rv == -1 && errno != EINTR)
+ qDebug("Semop lock failure %s",strerror(errno));
+ }
+#else
+ sembuf sops;
+ sops.sem_num = 0;
+ sops.sem_flg = SEM_UNDO;
+
+ if (t == Write) {
+ sops.sem_op = -MAX_LOCKS;
+ type = Write;
+ } else {
+ sops.sem_op = -1;
+ type = Read;
+ }
+
+ int rv;
+ do {
+ rv = semop(data->id,&sops,1);
+ if (rv == -1 && errno != EINTR)
+ qDebug("Semop lock failure %s",strerror(errno));
+ } while (rv == -1 && errno == EINTR);
+#endif
+ }
+ data->count++;
+}
+
+/*!
+ \fn void QLock::unlock()
+
+ Unlocks the semaphore. If other processes were blocking waiting to
+ lock() the semaphore, one of them will wake up and succeed in
+ lock()ing.
+*/
+
+void QLock::unlock()
+{
+ if(data->count) {
+ data->count--;
+ if(!data->count) {
+#ifdef Q_NO_SEMAPHORE
+ for(int rv=1; rv;) {
+ rv = flock(data->id, LOCK_UN);
+ if (rv == -1 && errno != EINTR)
+ qDebug("Semop lock failure %s",strerror(errno));
+ }
+#else
+ sembuf sops;
+ sops.sem_num = 0;
+ sops.sem_op = 1;
+ sops.sem_flg = SEM_UNDO;
+ if (type == Write)
+ sops.sem_op = MAX_LOCKS;
+
+ int rv;
+ do {
+ rv = semop(data->id,&sops,1);
+ if (rv == -1 && errno != EINTR)
+ qDebug("Semop unlock failure %s",strerror(errno));
+ } while (rv == -1 && errno == EINTR);
+#endif
+ }
+ } else {
+ qDebug("Unlock without corresponding lock");
+ }
+}
+
+/*!
+ \fn bool QLock::locked() const
+
+ Returns true if the lock is currently held by the current process;
+ otherwise returns false.
+*/
+
+bool QLock::locked() const
+{
+ return (data->count > 0);
+}
+
+QT_END_NAMESPACE
+
+#endif // QT_NO_QWS_MULTIPROCESS
+
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