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****************************************************************************/

#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;

        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