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Branched from the monolithic repo, Qt master branch, at commit
896db169ea224deb96c59ce8af800d019de63f12

1 files changed, 612 insertions, 0 deletions

diff --git a/src/corelib/kernel/qsharedmemory.cpp b/src/corelib/kernel/qsharedmemory.cpp
new file mode 100644
index 0000000000..78715a1966
--- /dev/null
+++ b/src/corelib/kernel/qsharedmemory.cpp
@@ -0,0 +1,612 @@
+/****************************************************************************
+**
+** 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 QtCore 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 "qsharedmemory.h"
+#include "qsharedmemory_p.h"
+#include "qsystemsemaphore.h"
+#include <qdir.h>
+#include <qcryptographichash.h>
+#ifdef Q_OS_SYMBIAN
+#include <e32const.h>
+#endif
+#include <qdebug.h>
+
+QT_BEGIN_NAMESPACE
+
+#if !(defined(QT_NO_SHAREDMEMORY) && defined(QT_NO_SYSTEMSEMAPHORE))
+/*!
+    \internal
+
+    Generate a string from the key which can be any unicode string into
+    the subset that the win/unix kernel allows.
+
+    On Unix this will be a file name
+    On Symbian key will be truncated to 80 characters
+  */
+QString
+QSharedMemoryPrivate::makePlatformSafeKey(const QString &key,
+					  const QString &prefix)
+{
+    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);
+#else
+    return QDir::tempPath() + QLatin1Char('/') + result;
+#endif
+}
+#endif // QT_NO_SHAREDMEMORY && QT_NO_SHAREDMEMORY
+
+#ifndef QT_NO_SHAREDMEMORY
+
+/*!
+  \class QSharedMemory
+  \since 4.4
+
+  \brief The QSharedMemory class provides access to a shared memory segment.
+
+  QSharedMemory provides access to a shared memory segment by multiple
+  threads and processes. It also provides a way for a single thread or
+  process to lock the memory for exclusive access.
+
+  When using this class, be aware of the following platform
+  differences:
+
+  \list
+
+  \o Windows: QSharedMemory does not "own" the shared memory segment.
+  When all threads or processes that have an instance of QSharedMemory
+  attached to a particular shared memory segment have either destroyed
+  their instance of QSharedMemory or exited, the Windows kernel
+  releases the shared memory segment automatically.
+
+  \o Unix: QSharedMemory "owns" the shared memory segment. When the
+  last thread or process that has an instance of QSharedMemory
+  attached to a particular shared memory segment detaches from the
+  segment by destroying its instance of QSharedMemory, the Unix kernel
+  release the shared memory segment. But if that last thread or
+  process crashes without running the QSharedMemory destructor, the
+  shared memory segment survives the crash.
+
+  \o HP-UX: Only one attach to a shared memory segment is allowed per
+  process. This means that QSharedMemory should not be used across
+  multiple threads in the same process in HP-UX.
+
+  \o Symbian: QSharedMemory does not "own" the shared memory segment.
+  When all threads or processes that have an instance of QSharedMemory
+  attached to a particular shared memory segment have either destroyed
+  their instance of QSharedMemory or exited, the Symbian kernel
+  releases the shared memory segment automatically.
+  Also, access to a shared memory segment cannot be limited to read-only
+  in Symbian.
+
+  \endlist
+
+  Remember to lock the shared memory with lock() before reading from
+  or writing to the shared memory, and remember to release the lock
+  with unlock() after you are done.
+
+  Unlike QtSharedMemory, QSharedMemory automatically destroys the
+  shared memory segment when the last instance of QSharedMemory is
+  detached from the segment, and no references to the segment
+  remain. Do not mix using QtSharedMemory and QSharedMemory. Port
+  everything to QSharedMemory.
+
+  \warning QSharedMemory changes the key in a Qt-specific way, unless otherwise
+  specified. Interoperation with non-Qt applications is achieved by first creating
+  a default shared memory with QSharedMemory() and then setting a native key with
+  setNativeKey(). When using native keys, shared memory is not protected against
+  multiple accesses on it (e.g. unable to lock()) and a user-defined mechanism
+  should be used to achieve a such protection.
+ */
+
+/*!
+  \overload QSharedMemory()
+
+  Constructs a shared memory object with the given \a parent.  The
+  shared memory object's key is not set by the constructor, so the
+  shared memory object does not have an underlying shared memory
+  segment attached. The key must be set with setKey() or setNativeKey()
+  before create() or attach() can be used.
+
+  \sa setKey()
+ */
+QSharedMemory::QSharedMemory(QObject *parent)
+  : QObject(*new QSharedMemoryPrivate, parent)
+{
+}
+
+/*!
+  Constructs a shared memory object with the given \a parent and with
+  its key set to \a key. Because its key is set, its create() and
+  attach() functions can be called.
+
+  \sa setKey(), create(), attach()
+ */
+QSharedMemory::QSharedMemory(const QString &key, QObject *parent)
+    : QObject(*new QSharedMemoryPrivate, parent)
+{
+    setKey(key);
+}
+
+/*!
+  The destructor clears the key, which forces the shared memory object
+  to \l {detach()} {detach} from its underlying shared memory
+  segment. If this shared memory object is the last one connected to
+  the shared memory segment, the detach() operation destroys the
+  shared memory segment.
+
+  \sa detach() isAttached()
+ */
+QSharedMemory::~QSharedMemory()
+{
+    setKey(QString());
+}
+
+/*!
+  Sets the platform independent \a key for this shared memory object. If \a key
+  is the same as the current key, the function returns without doing anything.
+
+  You can call key() to retrieve the platform independent key. Internally,
+  QSharedMemory converts this key into a platform specific key. If you instead
+  call nativeKey(), you will get the platform specific, converted key.
+
+  If the shared memory object is attached to an underlying shared memory
+  segment, it will \l {detach()} {detach} from it before setting the new key.
+  This function does not do an attach().
+
+  \sa key() nativeKey() isAttached()
+*/
+void QSharedMemory::setKey(const QString &key)
+{
+    Q_D(QSharedMemory);
+    if (key == d->key && d->makePlatformSafeKey(key) == d->nativeKey)
+        return;
+
+    if (isAttached())
+        detach();
+    d->cleanHandle();
+    d->key = key;
+    d->nativeKey = d->makePlatformSafeKey(key);
+}
+
+/*!
+  \since 4.8
+
+  Sets the native, platform specific, \a key for this shared memory object. If
+  \a key is the same as the current native key, the function returns without
+  doing anything. If all you want is to assign a key to a segment, you should
+  call setKey() instead.
+
+  You can call nativeKey() to retrieve the native key. If a native key has been
+  assigned, calling key() will return a null string.
+
+  If the shared memory object is attached to an underlying shared memory
+  segment, it will \l {detach()} {detach} from it before setting the new key.
+  This function does not do an attach().
+
+  The application will not be portable if you set a native key.
+
+  \sa nativeKey() key() isAttached()
+*/
+void QSharedMemory::setNativeKey(const QString &key)
+{
+    Q_D(QSharedMemory);
+    if (key == d->nativeKey && d->key.isNull())
+        return;
+
+    if (isAttached())
+        detach();
+    d->cleanHandle();
+    d->key = QString();
+    d->nativeKey = key;
+}
+
+bool QSharedMemoryPrivate::initKey()
+{
+    if (!cleanHandle())
+        return false;
+#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 = QString();
+    error = QSharedMemory::NoError;
+    return true;
+}
+
+/*!
+  Returns the key assigned with setKey() to this shared memory, or a null key
+  if no key has been assigned, or if the segment is using a nativeKey(). The
+  key is the identifier used by Qt applications to identify the shared memory
+  segment.
+
+  You can find the native, platform specific, key used by the operating system
+  by calling nativeKey().
+
+  \sa setKey() setNativeKey()
+ */
+QString QSharedMemory::key() const
+{
+    Q_D(const QSharedMemory);
+    return d->key;
+}
+
+/*!
+  \since 4.8
+
+  Returns the native, platform specific, key for this shared memory object. The
+  native key is the identifier used by the operating system to identify the
+  shared memory segment.
+
+  You can use the native key to access shared memory segments that have not
+  been created by Qt, or to grant shared memory access to non-Qt applications.
+
+  \sa setKey() setNativeKey()
+*/
+QString QSharedMemory::nativeKey() const
+{
+    Q_D(const QSharedMemory);
+    return d->nativeKey;
+}
+
+/*!
+  Creates a shared memory segment of \a size bytes with the key passed to the
+  constructor, set with setKey() or set with setNativeKey(), then attaches to
+  the new shared memory segment with the given access \a mode and returns
+  \tt true. If a shared memory segment identified by the key already exists,
+  the attach operation is not performed and \tt false is returned. When the
+  return value is \tt false, call error() to determine which error occurred.
+
+  \sa error()
+ */
+bool QSharedMemory::create(int size, AccessMode mode)
+{
+    Q_D(QSharedMemory);
+
+    if (!d->initKey())
+        return false;
+
+#ifndef QT_NO_SYSTEMSEMAPHORE
+#ifndef Q_OS_WIN
+    // Take ownership and force set initialValue because the semaphore
+    // might have already existed from a previous crash.
+    d->systemSemaphore.setKey(d->key, 1, QSystemSemaphore::Create);
+#endif
+#endif
+
+    QString function = QLatin1String("QSharedMemory::create");
+#ifndef QT_NO_SYSTEMSEMAPHORE
+    QSharedMemoryLocker lock(this);
+    if (!d->key.isNull() && !d->tryLocker(&lock, function))
+        return false;
+#endif
+
+    if (size <= 0) {
+        d->error = QSharedMemory::InvalidSize;
+        d->errorString =
+	    QSharedMemory::tr("%1: create size is less then 0").arg(function);
+        return false;
+    }
+
+    if (!d->create(size))
+        return false;
+
+    return d->attach(mode);
+}
+
+/*!
+  Returns the size of the attached shared memory segment. If no shared
+  memory segment is attached, 0 is returned.
+
+  \sa create() attach()
+ */
+int QSharedMemory::size() const
+{
+    Q_D(const QSharedMemory);
+    return d->size;
+}
+
+/*!
+  \enum QSharedMemory::AccessMode
+
+  \value ReadOnly The shared memory segment is read-only. Writing to
+  the shared memory segment is not allowed. An attempt to write to a
+  shared memory segment created with ReadOnly causes the program to
+  abort.
+
+  \value ReadWrite Reading and writing the shared memory segment are
+  both allowed.
+*/
+
+/*!
+  Attempts to attach the process to the shared memory segment
+  identified by the key that was passed to the constructor or to a
+  call to setKey() or setNativeKey(). The access \a mode is \l {QSharedMemory::}
+  {ReadWrite} by default. It can also be \l {QSharedMemory::}
+  {ReadOnly}. Returns true if the attach operation is successful. If
+  false is returned, call error() to determine which error occurred.
+  After attaching the shared memory segment, a pointer to the shared
+  memory can be obtained by calling data().
+
+  \sa isAttached(), detach(), create()
+ */
+bool QSharedMemory::attach(AccessMode mode)
+{
+    Q_D(QSharedMemory);
+
+    if (isAttached() || !d->initKey())
+        return false;
+#ifndef QT_NO_SYSTEMSEMAPHORE
+    QSharedMemoryLocker lock(this);
+    if (!d->key.isNull() && !d->tryLocker(&lock, QLatin1String("QSharedMemory::attach")))
+        return false;
+#endif
+
+    if (isAttached() || !d->handle())
+        return false;
+
+    return d->attach(mode);
+}
+
+/*!
+  Returns true if this process is attached to the shared memory
+  segment.
+
+  \sa attach(), detach()
+ */
+bool QSharedMemory::isAttached() const
+{
+    Q_D(const QSharedMemory);
+    return (0 != d->memory);
+}
+
+/*!
+  Detaches the process from the shared memory segment. If this was the
+  last process attached to the shared memory segment, then the shared
+  memory segment is released by the system, i.e., the contents are
+  destroyed. The function returns true if it detaches the shared
+  memory segment. If it returns false, it usually means the segment
+  either isn't attached, or it is locked by another process.
+
+  \sa attach(), isAttached()
+ */
+bool QSharedMemory::detach()
+{
+    Q_D(QSharedMemory);
+    if (!isAttached())
+        return false;
+
+#ifndef QT_NO_SYSTEMSEMAPHORE
+    QSharedMemoryLocker lock(this);
+    if (!d->key.isNull() && !d->tryLocker(&lock, QLatin1String("QSharedMemory::detach")))
+        return false;
+#endif
+
+    return d->detach();
+}
+
+/*!
+  Returns a pointer to the contents of the shared memory segment, if
+  one is attached. Otherwise it returns null. Remember to lock the
+  shared memory with lock() before reading from or writing to the
+  shared memory, and remember to release the lock with unlock() after
+  you are done.
+
+  \sa attach()
+ */
+void *QSharedMemory::data()
+{
+    Q_D(QSharedMemory);
+    return d->memory;
+}
+
+/*!
+  Returns a const pointer to the contents of the shared memory
+  segment, if one is attached. Otherwise it returns null. Remember to
+  lock the shared memory with lock() before reading from or writing to
+  the shared memory, and remember to release the lock with unlock()
+  after you are done.
+
+  \sa attach() create()
+ */
+const void* QSharedMemory::constData() const
+{
+    Q_D(const QSharedMemory);
+    return d->memory;
+}
+
+/*!
+  \overload data()
+ */
+const void *QSharedMemory::data() const
+{
+    Q_D(const QSharedMemory);
+    return d->memory;
+}
+
+#ifndef QT_NO_SYSTEMSEMAPHORE
+/*!
+  This is a semaphore that locks the shared memory segment for access
+  by this process and returns true. If another process has locked the
+  segment, this function blocks until the lock is released. Then it
+  acquires the lock and returns true. If this function returns false,
+  it means that you have ignored a false return from create() or attach(),
+  that you have set the key with setNativeKey() or that
+  QSystemSemaphore::acquire() failed due to an unknown system error.
+
+  \sa unlock(), data(), QSystemSemaphore::acquire()
+ */
+bool QSharedMemory::lock()
+{
+    Q_D(QSharedMemory);
+    if (d->lockedByMe) {
+        qWarning("QSharedMemory::lock: already locked");
+        return true;
+    }
+    if (d->systemSemaphore.acquire()) {
+        d->lockedByMe = true;
+        return true;
+    }
+    QString function = QLatin1String("QSharedMemory::lock");
+    d->errorString = QSharedMemory::tr("%1: unable to lock").arg(function);
+    d->error = QSharedMemory::LockError;
+    return false;
+}
+
+/*!
+  Releases the lock on the shared memory segment and returns true, if
+  the lock is currently held by this process. If the segment is not
+  locked, or if the lock is held by another process, nothing happens
+  and false is returned.
+
+  \sa lock()
+ */
+bool QSharedMemory::unlock()
+{
+    Q_D(QSharedMemory);
+    if (!d->lockedByMe)
+        return false;
+    d->lockedByMe = false;
+    if (d->systemSemaphore.release())
+        return true;
+    QString function = QLatin1String("QSharedMemory::unlock");
+    d->errorString = QSharedMemory::tr("%1: unable to unlock").arg(function);
+    d->error = QSharedMemory::LockError;
+    return false;
+}
+#endif // QT_NO_SYSTEMSEMAPHORE
+
+/*!
+  \enum QSharedMemory::SharedMemoryError
+
+  \value NoError No error occurred.
+
+  \value PermissionDenied The operation failed because the caller
+  didn't have the required permissions.
+
+  \value InvalidSize A create operation failed because the requested
+  size was invalid.
+
+  \value KeyError The operation failed because of an invalid key.
+
+  \value AlreadyExists A create() operation failed because a shared
+  memory segment with the specified key already existed.
+
+  \value NotFound An attach() failed because a shared memory segment
+  with the specified key could not be found.
+
+  \value LockError The attempt to lock() the shared memory segment
+  failed because create() or attach() failed and returned false, or
+  because a system error occurred in QSystemSemaphore::acquire().
+
+  \value OutOfResources A create() operation failed because there was
+  not enough memory available to fill the request.
+
+  \value UnknownError Something else happened and it was bad.
+*/
+
+/*!
+  Returns a value indicating whether an error occurred, and, if so,
+  which error it was.
+
+  \sa errorString()
+ */
+QSharedMemory::SharedMemoryError QSharedMemory::error() const
+{
+    Q_D(const QSharedMemory);
+    return d->error;
+}
+
+/*!
+  Returns a text description of the last error that occurred. If
+  error() returns an \l {QSharedMemory::SharedMemoryError} {error
+  value}, call this function to get a text string that describes the
+  error.
+
+  \sa error()
+ */
+QString QSharedMemory::errorString() const
+{
+    Q_D(const QSharedMemory);
+    return d->errorString;
+}
+
+#endif // QT_NO_SHAREDMEMORY
+
+QT_END_NAMESPACE