QSharedMemoryPrivate Class Reference

#include <qsharedmemory_p.h>

Inheritance diagram for QSharedMemoryPrivate:

Public Functions
bool	attach (QSharedMemory::AccessMode mode)
void	cleanHandle ()
bool	create (int size)
bool	detach ()
HANDLE	handle ()
	If not already made create the handle used for accessing the shared memory. More...
bool	initKey ()
	QSharedMemoryPrivate ()
void	setErrorString (const QString &function)
bool	tryLocker (QSharedMemoryLocker *locker, const QString &function)
Public Functions inherited from QObjectPrivate
void	_q_reregisterTimers (void *pointer)
void	addConnection (int signal, Connection *c)
void	cleanConnectionLists ()
void	connectNotify (const char *signal)
void	deleteChildren ()
void	disconnectNotify (const char *signal)
bool	isSender (const QObject *receiver, const char *signal) const
bool	isSignalConnected (uint signalIdx) const
	Returns true if the signal with index signal_index from object sender is connected. More...
void	moveToThread_helper ()
	QObjectPrivate (int version=QObjectPrivateVersion)
QObjectList	receiverList (const char *signal) const
QObjectList	senderList () const
void	setParent_helper (QObject *)
void	setThreadData_helper (QThreadData *currentData, QThreadData *targetData)
int	signalIndex (const char *signalName) const
	Returns the signal index used in the internal connectionLists vector. More...
virtual	~QObjectPrivate ()
Public Functions inherited from QObjectData
virtual	~QObjectData ()=0

Static Public Functions
static int	createUnixKeyFile (const QString &fileName)
	Creates the unix file if needed. More...
static QString	makePlatformSafeKey (const QString &key, const QString &prefix=QLatin1String("qipc_sharedmemory_"))
	Generate a string from the key which can be any unicode string into the subset that the win/unix kernel allows. More...
Static Public Functions inherited from QObjectPrivate
static void	clearGuards (QObject *)
static QObjectPrivate *	get (QObject *o)
static void	resetCurrentSender (QObject *receiver, Sender *currentSender, Sender *previousSender)
static Sender *	setCurrentSender (QObject *receiver, Sender *sender)
static void	signalSignature (const QMetaMethod &signal, QVarLengthArray< char > *result)

Public Variables
QSharedMemory::SharedMemoryError	error
QString	errorString
QString	key
bool	lockedByMe
void *	memory
QString	nativeKey
int	size
QSystemSemaphore	systemSemaphore
Public Variables inherited from QObjectPrivate
union {
QObject *   currentChildBeingDeleted
QAbstractDeclarativeData *   declarativeData
};
quint32	connectedSignals [2]
QObjectConnectionListVector *	connectionLists
Sender *	currentSender
QList< QPointer< QObject > >	eventFilters
ExtraData *	extraData
QString	objectName
Connection *	senders
QAtomicPointer< QtSharedPointer::ExternalRefCountData >	sharedRefcount
QThreadData *	threadData
void *	unused
Public Variables inherited from QObjectData
uint	blockSig: 1
QObjectList	children
uint	hasGuards: 1
uint	inEventHandler: 1
uint	inThreadChangeEvent: 1
uint	isWidget: 1
QMetaObject *	metaObject
uint	ownObjectName: 1
QObject *	parent
uint	pendTimer: 1
int	postedEvents
QObject *	q_ptr
uint	receiveChildEvents: 1
uint	sendChildEvents: 1
uint	unused: 22
uint	wasDeleted: 1

Properties
HANDLE	hand

Additional Inherited Members
Public Types inherited from QObjectPrivate
typedef void(*	StaticMetaCallFunction) (QObject *, QMetaObject::Call, int, void **)

Detailed Description

Definition at line 115 of file qsharedmemory_p.h.

Constructors and Destructors

QSharedMemoryPrivate()

QSharedMemoryPrivate::QSharedMemoryPrivate

(

)

Definition at line 72 of file qsharedmemory_unix.cpp.

    : QObjectPrivate(), memory(0), size(0), error(QSharedMemory::NoError),
#ifndef QT_NO_SYSTEMSEMAPHORE
      systemSemaphore(QString()), lockedByMe(false),
#endif
#ifndef QT_POSIX_IPC
      unix_key(0)
#else
      hand(0)
#endif
{
}

Functions

attach()

bool QSharedMemoryPrivate::attach

(

QSharedMemory::AccessMode

mode

)

Definition at line 298 of file qsharedmemory_unix.cpp.

{
#ifndef QT_POSIX_IPC
    // grab the shared memory segment id
    int id = shmget(unix_key, 0, (mode == QSharedMemory::ReadOnly ? 0400 : 0600));
    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;
    }
#else
    QByteArray shmName = QFile::encodeName(makePlatformSafeKey(key));

    int oflag = (mode == QSharedMemory::ReadOnly ? O_RDONLY : O_RDWR);
    mode_t omode = (mode == QSharedMemory::ReadOnly ? 0444 : 0660);

    EINTR_LOOP(hand, shm_open(shmName.constData(), oflag, omode));
    if (hand == -1) {
        QString function = QLatin1String("QSharedMemory::attach (shm_open)");
        switch (errno) {
        case ENAMETOOLONG:
        case EINVAL:
            errorString = QSharedMemory::tr("%1: bad name").arg(function);
            error = QSharedMemory::KeyError;
            break;
        default:
            setErrorString(function);
        }
        hand = 0;
        return false;
    }

    // grab the size
    QT_STATBUF st;
    if (QT_FSTAT(hand, &st) == -1) {
        setErrorString(QLatin1String("QSharedMemory::attach (fstat)"));
        cleanHandle();
        return false;
    }
    size = st.st_size;

    // grab the memory
    int mprot = (mode == QSharedMemory::ReadOnly ? PROT_READ : PROT_READ | PROT_WRITE);
    memory = mmap(0, size, mprot, MAP_SHARED, hand, 0);
    if (memory == MAP_FAILED || !memory) {
        setErrorString(QLatin1String("QSharedMemory::attach (mmap)"));
        cleanHandle();
        memory = 0;
        size = 0;
        return false;
    }
#endif // QT_POSIX_IPC

    return true;
}

cleanHandle()

void QSharedMemoryPrivate::cleanHandle

(

)

Definition at line 217 of file qsharedmemory_unix.cpp.

Referenced by attach(), and detach().

{
#ifndef QT_POSIX_IPC
    unix_key = 0;
#else
    qt_safe_close(hand);
    hand = 0;
#endif
}

create()

bool QSharedMemoryPrivate::create

(

int

size

)

Definition at line 227 of file qsharedmemory_unix.cpp.

{
#ifndef QT_POSIX_IPC
    // build file if needed
    int built = createUnixKeyFile(nativeKey);
    if (built == -1) {
        errorString = QSharedMemory::tr("%1: unable to make key").arg(QLatin1String("QSharedMemory::create"));
        error = QSharedMemory::KeyError;
        return false;
    }
    bool createdFile = built == 1;

    // get handle
    if (!handle()) {
        if (createdFile)
            QFile::remove(nativeKey);
        return false;
    }

    // create
    if (-1 == shmget(unix_key, size, 0600 | IPC_CREAT | IPC_EXCL)) {
        QString function = QLatin1String("QSharedMemory::create");
        switch (errno) {
        case EINVAL:
            errorString = QSharedMemory::tr("%1: system-imposed size restrictions").arg(function);
            error = QSharedMemory::InvalidSize;
            break;
        default:
            setErrorString(function);
        }
        if (createdFile && error != QSharedMemory::AlreadyExists)
            QFile::remove(nativeKey);
        return false;
    }
#else
    if (!handle())
        return false;

    QByteArray shmName = QFile::encodeName(makePlatformSafeKey(key));

    int fd;
    EINTR_LOOP(fd, shm_open(shmName.constData(), O_RDWR | O_CREAT | O_EXCL, 0666));
    if (fd == -1) {
        QString function = QLatin1String("QSharedMemory::create");
        switch (errno) {
        case ENAMETOOLONG:
        case EINVAL:
            errorString = QSharedMemory::tr("%1: bad name").arg(function);
            error = QSharedMemory::KeyError;
            break;
        default:
            setErrorString(function);
        }
        return false;
    }

    // the size may only be set once; ignore errors
    int ret;
    EINTR_LOOP(ret, ftruncate(fd, size));
    if (ret == -1) {
        setErrorString(QLatin1String("QSharedMemory::create (ftruncate)"));
        qt_safe_close(fd);
        return false;
    }

    qt_safe_close(fd);
#endif // QT_POSIX_IPC

    return true;
}

createUnixKeyFile()

int QSharedMemoryPrivate::createUnixKeyFile ( const QString &  fileName )

static

Creates the unix file if needed.

Warning

This function is not part of the public interface.

returns true if the unix file was created.

-1 error 0 already existed 1 created

Definition at line 191 of file qsharedmemory_unix.cpp.

Referenced by create(), and QSystemSemaphorePrivate::handle().

{
#ifndef QT_POSIX_IPC
    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 {
        qt_safe_close(fd);
    }
    return 1;
#else
    Q_UNUSED(fileName);
    // nothing to do
    return -1;
#endif
}

detach()

bool QSharedMemoryPrivate::detach

(

)

Definition at line 370 of file qsharedmemory_unix.cpp.

{
#ifndef QT_POSIX_IPC
    // 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;
    size = 0;

    // Get the number of current attachments
    int id = shmget(unix_key, 0, 0400);
    cleanHandle();

    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::detach"));
            switch (errno) {
            case EINVAL:
                return true;
            default:
                return false;
            }
        }

        // remove file
        if (!QFile::remove(nativeKey))
            return false;
    }
#else
    // detach from the memory segment
    if (munmap(memory, size) == -1) {
        setErrorString(QLatin1String("QSharedMemory::detach (munmap)"));
        return false;
    }
    memory = 0;
    size = 0;

    // get the number of current attachments
    int shm_nattch = 0;
    QT_STATBUF st;
    if (QT_FSTAT(hand, &st) == 0) {
        // subtract 2 from linkcount: one for our own open and one for the dir entry
        shm_nattch = st.st_nlink - 2;
    }
    cleanHandle();
    // if there are no attachments then unlink the shared memory
    if (shm_nattch == 0) {
        QByteArray shmName = QFile::encodeName(makePlatformSafeKey(key));
        if (shm_unlink(shmName.constData()) == -1 && errno != ENOENT)
            setErrorString(QLatin1String("QSharedMemory::detach (shm_unlink)"));
    }
#endif // QT_POSIX_IPC

    return true;
}

handle()

HANDLE QSharedMemoryPrivate::handle

(

)

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

Warning

This function is not part of the public interface.

Definition at line 133 of file qsharedmemory_unix.cpp.

Referenced by create().

{
    // already made
    if (unix_key)
        return unix_key;

    // don't allow making handles on empty keys
    if (nativeKey.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
    if (!QFile::exists(nativeKey)) {
        errorString = QSharedMemory::tr("%1: UNIX key file doesn't exist").arg(QLatin1String("QSharedMemory::handle"));
        error = QSharedMemory::NotFound;
        return 0;
    }

    unix_key = ftok(QFile::encodeName(nativeKey).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;
}

initKey()

bool QSharedMemoryPrivate::initKey

(

)

Definition at line 271 of file qsharedmemory.cpp.

{
    cleanHandle();

#ifndef QT_NO_SYSTEMSEMAPHORE
    systemSemaphore.setKey(QString(), 1);
    systemSemaphore.setKey(key, 1);
    if (systemSemaphore.error() != QSystemSemaphore::NoError) {
        QString function = QLatin1String("QSharedMemoryPrivate::initKey");
        errorString = QSharedMemory::tr("%1: unable to set key on lock").arg(function);
        switch(systemSemaphore.error()) {
        case QSystemSemaphore::PermissionDenied:
            error = QSharedMemory::PermissionDenied;
            break;
        case QSystemSemaphore::KeyError:
            error = QSharedMemory::KeyError;
            break;
        case QSystemSemaphore::AlreadyExists:
            error = QSharedMemory::AlreadyExists;
            break;
        case QSystemSemaphore::NotFound:
            error = QSharedMemory::NotFound;
            break;
        case QSystemSemaphore::OutOfResources:
            error = QSharedMemory::OutOfResources;
            break;
        case QSystemSemaphore::UnknownError:
        default:
            error = QSharedMemory::UnknownError;
            break;
        }
        return false;
    }
#endif
    errorString.clear();
    error = QSharedMemory::NoError;
    return true;
}

makePlatformSafeKey()

QString QSharedMemoryPrivate::makePlatformSafeKey ( const QString &  key, const QString &  prefix = QLatin1String("qipc_sharedmemory_")  )

static

Generate a string from the key which can be any unicode string into the subset that the win/unix kernel allows.

Warning

This function is not part of the public interface.

On Unix this will be a file name On Symbian key will be truncated to 80 characters

Definition at line 68 of file qsharedmemory.cpp.

Referenced by attach(), create(), detach(), handle(), and QSystemSemaphorePrivate::makeKeyFileName().

{
    if (key.isEmpty())
        return QString();

    QString result = prefix;

    QString part1 = key;
    part1.replace(QRegExp(QLatin1String("[^A-Za-z]")), QString());
    result.append(part1);

    QByteArray hex = QCryptographicHash::hash(key.toUtf8(), QCryptographicHash::Sha1).toHex();
    result.append(QLatin1String(hex));
#ifdef Q_OS_WIN
    return result;
#elif defined(Q_OS_SYMBIAN)
    return result.left(KMaxKernelName);
#elif defined(QT_POSIX_IPC)
    return QLatin1Char('/') + result;
#else
    return QDir::tempPath() + QLatin1Char('/') + result;
#endif
}

setErrorString()

void QSharedMemoryPrivate::setErrorString

(

const QString &

function

)

Definition at line 85 of file qsharedmemory_unix.cpp.

Referenced by attach(), create(), and detach().

{
    // EINVAL is handled in functions so they can give better error strings
    switch (errno) {
    case EACCES:
    case EPERM:
        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 EAGAIN:
    case EMFILE:
    case ENFILE:
    case ENOMEM:
    case ENOSPC:
        errorString = QSharedMemory::tr("%1: out of resources").arg(function);
        error = QSharedMemory::OutOfResources;
        break;
    case EOVERFLOW:
        errorString = QSharedMemory::tr("%1: invalid size").arg(function);
        error = QSharedMemory::InvalidSize;
        break;
    default:
        errorString = QSharedMemory::tr("%1: unknown error %2").arg(function).arg(errno);
        error = QSharedMemory::UnknownError;
#ifdef QSHAREDMEMORY_DEBUG
        qDebug() << errorString << "key" << key << "errno" << errno << EINVAL;
#endif
        break;
    }
}

tryLocker()

bool QSharedMemoryPrivate::tryLocker ( QSharedMemoryLocker *  locker, const QString &  function  )

inline

Definition at line 156 of file qsharedmemory_p.h.

                                                                                {
        if (!locker->lock()) {
            errorString = QSharedMemory::tr("%1: unable to lock").arg(function);
            error = QSharedMemory::LockError;
            return false;
        }
        return true;
    }

Properties

error

QSharedMemory::SharedMemoryError QSharedMemoryPrivate::error

Definition at line 126 of file qsharedmemory_p.h.

Referenced by attach(), create(), detach(), handle(), and setErrorString().

errorString

QString QSharedMemoryPrivate::errorString

Definition at line 127 of file qsharedmemory_p.h.

Referenced by attach(), create(), detach(), handle(), and setErrorString().

hand

HANDLE QSharedMemoryPrivate::hand

private

Definition at line 168 of file qsharedmemory_p.h.

Referenced by attach(), cleanHandle(), and detach().

key

QString QSharedMemoryPrivate::key

Definition at line 124 of file qsharedmemory_p.h.

Referenced by attach(), create(), detach(), handle(), makePlatformSafeKey(), and setErrorString().

lockedByMe

bool QSharedMemoryPrivate::lockedByMe

Definition at line 130 of file qsharedmemory_p.h.

memory

void* QSharedMemoryPrivate::memory

Definition at line 122 of file qsharedmemory_p.h.

Referenced by attach(), and detach().

nativeKey

QString QSharedMemoryPrivate::nativeKey

Definition at line 125 of file qsharedmemory_p.h.

Referenced by create(), detach(), and handle().

size

int QSharedMemoryPrivate::size

Definition at line 123 of file qsharedmemory_p.h.

Referenced by attach(), and detach().

systemSemaphore

QSystemSemaphore QSharedMemoryPrivate::systemSemaphore

Definition at line 129 of file qsharedmemory_p.h.

---

The documentation for this class was generated from the following files:

• /src/corelib/kernel/qsharedmemory_p.h
• /src/corelib/kernel/qsharedmemory.cpp
• /src/corelib/kernel/qsharedmemory_unix.cpp
• /src/corelib/kernel/qsharedmemory_win.cpp