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

#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 <unistd.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))

#if defined(Q_OS_SYMBIAN)

int createUnixKeyFile(const QString &fileName)

{

    if (QFile::exists(fileName))

        return 0;

    int fd = open(QFile::encodeName(fileName).constData(),

            O_EXCL | O_CREAT | O_RDWR, 0640);

    if (-1 == fd) {

        if (errno == EEXIST)

            return 0;

        return -1;

    } else {

        close(fd);

    }

    return 1;

}

#endif

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

#if defined(Q_OS_SYMBIAN)

    int built = createUnixKeyFile(fileName);

#else

    int built = QSharedMemoryPrivate::createUnixKeyFile(fileName);

#endif

    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;

}