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

**

** Copyright (C) 2009 Nokia Corporation and/or its subsidiary(-ies).

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** Contact: Nokia Corporation (qt-info@nokia.com)

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** This file is part of the QtCore module of the Qt Toolkit.

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** 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.

**

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** rights.  These rights are described in the Nokia Qt LGPL Exception

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** $QT_END_LICENSE$

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

#include "qplatformdefs.h"

#include "qsharedmemory.h"

#include "qsharedmemory_p.h"

#include "qsystemsemaphore.h"

#include <qdir.h>

#include <qdebug.h>

#include <errno.h>

#ifndef QT_NO_SHAREDMEMORY

#include <sys/types.h>

#include <sys/ipc.h>

#include <sys/shm.h>

#include <sys/types.h>

#include <sys/stat.h>

#include <fcntl.h>

#include <unistd.h>

#include "private/qcore_unix_p.h"

QT_BEGIN_NAMESPACE

QSharedMemoryPrivate::QSharedMemoryPrivate()

    : QObjectPrivate(), memory(0), size(0), error(QSharedMemory::NoError),

#ifndef QT_NO_SYSTEMSEMAPHORE

      systemSemaphore(QString()), lockedByMe(false),

#endif

      unix_key(0)

{

}

void QSharedMemoryPrivate::setErrorString(const QString &function)

{

    // EINVAL is handled in functions so they can give better error strings

    switch (errno) {

    case EACCES:

        errorString = QSharedMemory::tr("%1: permission denied").arg(function);

        error = QSharedMemory::PermissionDenied;

        break;

    case EEXIST:

        errorString = QSharedMemory::tr("%1: already exists").arg(function);

        error = QSharedMemory::AlreadyExists;

        break;

    case ENOENT:

        errorString = QSharedMemory::tr("%1: doesn't exist").arg(function);

        error = QSharedMemory::NotFound;

        break;

    case EMFILE:

    case ENOMEM:

    case ENOSPC:

        errorString = QSharedMemory::tr("%1: out of resources").arg(function);

        error = QSharedMemory::OutOfResources;

        break;

    default:

        errorString = QSharedMemory::tr("%1: unknown error %2").arg(function).arg(errno);

        error = QSharedMemory::UnknownError;

#if defined QSHAREDMEMORY_DEBUG

        qDebug() << errorString << "key" << key << "errno" << errno << EINVAL;

#endif

    }

}

/*!

    \internal

    If not already made create the handle used for accessing the shared memory.

*/

key_t QSharedMemoryPrivate::handle()

{

    // already made

    if (unix_key)

        return unix_key;

    // don't allow making handles on empty keys

    if (key.isEmpty()) {

        errorString = QSharedMemory::tr("%1: key is empty").arg(QLatin1String("QSharedMemory::handle:"));

        error = QSharedMemory::KeyError;

        return 0;

    }

    // ftok requires that an actual file exists somewhere

    QString fileName = makePlatformSafeKey(key);

    if (!QFile::exists(fileName)) {

        errorString = QSharedMemory::tr("%1: UNIX key file doesn't exist").arg(QLatin1String("QSharedMemory::handle:"));

        error = QSharedMemory::NotFound;

        return 0;

    }

    unix_key = ftok(QFile::encodeName(fileName).constData(), 'Q');

    if (-1 == unix_key) {

        errorString = QSharedMemory::tr("%1: ftok failed").arg(QLatin1String("QSharedMemory::handle:"));

        error = QSharedMemory::KeyError;

        unix_key = 0;

    }

    return unix_key;

}

#endif // QT_NO_SHAREDMEMORY

#if !(defined(QT_NO_SHAREDMEMORY) && defined(QT_NO_SYSTEMSEMAPHORE))

/*!

    \internal

    Creates the unix file if needed.

    returns true if the unix file was created.

    -1 error

     0 already existed

     1 created

  */

int QSharedMemoryPrivate::createUnixKeyFile(const QString &fileName)

{

    if (QFile::exists(fileName))

        return 0;

    int fd = qt_safe_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 // QT_NO_SHAREDMEMORY && QT_NO_SYSTEMSEMAPHORE

#ifndef QT_NO_SHAREDMEMORY

bool QSharedMemoryPrivate::cleanHandle()

{

    unix_key = 0;

    return true;

}

bool QSharedMemoryPrivate::create(int size)

{

    // build file if needed

    bool createdFile = false;

    int built = createUnixKeyFile(makePlatformSafeKey(key));

    if (built == -1) {

        errorString = QSharedMemory::tr("%1: unable to make key").arg(QLatin1String("QSharedMemory::handle:"));

        error = QSharedMemory::KeyError;

        return false;

    }

    if (built == 1) {

        createdFile = true;

    }

    // get handle

    if (!handle()) {

        if (createdFile)

            QFile::remove(makePlatformSafeKey(key));

        return false;

    }

    // create

    if (-1 == shmget(handle(), size, 0666 | IPC_CREAT | IPC_EXCL)) {

        QString function = QLatin1String("QSharedMemory::create");

        switch (errno) {

        case EINVAL:

            errorString = QSharedMemory::tr("%1: system-imposed size restrictions").arg(QLatin1String("QSharedMemory::handle"));

            error = QSharedMemory::InvalidSize;

            break;

        default:

            setErrorString(function);

        }

        if (createdFile && error != QSharedMemory::AlreadyExists)

            QFile::remove(makePlatformSafeKey(key));

        return false;

    }

    return true;

}

bool QSharedMemoryPrivate::attach(QSharedMemory::AccessMode mode)

{

    // grab the shared memory segment id

    if (!handle())

        return false;

    int id = shmget(handle(), 0, (mode == QSharedMemory::ReadOnly ? 0444 : 0660));

    if (-1 == id) {

        setErrorString(QLatin1String("QSharedMemory::attach (shmget)"));

        return false;

    }

    // grab the memory

    memory = shmat(id, 0, (mode == QSharedMemory::ReadOnly ? SHM_RDONLY : 0));

    if ((void*) - 1 == memory) {

        memory = 0;

        setErrorString(QLatin1String("QSharedMemory::attach (shmat)"));

        return false;

    }

    // grab the size

    shmid_ds shmid_ds;

    if (!shmctl(id, IPC_STAT, &shmid_ds)) {

        size = (int)shmid_ds.shm_segsz;

    } else {

        setErrorString(QLatin1String("QSharedMemory::attach (shmctl)"));

        return false;

    }

    return true;

}

bool QSharedMemoryPrivate::detach()

{

    // detach from the memory segment

    if (-1 == shmdt(memory)) {

        QString function = QLatin1String("QSharedMemory::detach");

        switch (errno) {

        case EINVAL:

            errorString = QSharedMemory::tr("%1: not attached").arg(function);

            error = QSharedMemory::NotFound;

            break;

        default:

            setErrorString(function);

        }

        return false;

    }

    memory = 0;

    // Get the number of current attachments

    if (!handle())

        return false;

    int id = shmget(handle(), 0, 0444);

    unix_key = 0;

    struct shmid_ds shmid_ds;

    if (0 != shmctl(id, IPC_STAT, &shmid_ds)) {

        switch (errno) {

        case EINVAL:

            return true;

        default:

            return false;

        }

    }

    // If there are no attachments then remove it.

    if (shmid_ds.shm_nattch == 0) {

        // mark for removal

        if (-1 == shmctl(id, IPC_RMID, &shmid_ds)) {

            setErrorString(QLatin1String("QSharedMemory::remove"));

            switch (errno) {

            case EINVAL:

                return true;

            default:

                return false;

            }

        }

        // remove file

        if (!QFile::remove(makePlatformSafeKey(key)))

            return false;

    }

    return true;

}

QT_END_NAMESPACE

#endif // QT_NO_SHAREDMEMORY