Add the QDBusUnixFileDescriptor class

This class holds one Unix file descriptor. It's implicitly shared, but
it makes a copy of your file descriptor (via dup(2) or dup2(2)).

This class is supposed to work even outside Unix systems, just that it
will never do anything.

Documentation in a later commit.

Task-number: QTBUG-17477

3 files changed, 282 insertions, 2 deletions

diff --git a/src/dbus/dbus.pro b/src/dbus/dbus.pro
index 52ed217..08c9ea1 100644
--- a/src/dbus/dbus.pro
+++ b/src/dbus/dbus.pro
@@ -59,7 +59,8 @@ HEADERS += $$PUB_HEADERS \
     qdbusintegrator_p.h \
     qdbuspendingcall_p.h \
     qdbus_symbols_p.h \
-    qdbusservicewatcher.h
+    qdbusservicewatcher.h \
+    qdbusunixfiledescriptor.h
 SOURCES += qdbusconnection.cpp \
     qdbusconnectioninterface.cpp \
     qdbuserror.cpp \
@@ -85,4 +86,5 @@ SOURCES += qdbusconnection.cpp \
     qdbuspendingcall.cpp \
     qdbuspendingreply.cpp \
     qdbus_symbols.cpp \
-    qdbusservicewatcher.cpp
+    qdbusservicewatcher.cpp \
+    qdbusunixfiledescriptor.cpp
diff --git a/src/dbus/qdbusunixfiledescriptor.cpp b/src/dbus/qdbusunixfiledescriptor.cpp
new file mode 100644
index 0000000..368753c
--- /dev/null
+++ b/src/dbus/qdbusunixfiledescriptor.cpp
@@ -0,0 +1,175 @@
+/****************************************************************************
+**
+** 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 FOO 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 "qdbusunixfiledescriptor.h"
+#include <QSharedData>
+
+#ifdef Q_OS_UNIX
+# include <private/qcore_unix_p.h>
+#endif
+
+class QDBusUnixFileDescriptorPrivate : public QSharedData {
+public:
+    QDBusUnixFileDescriptorPrivate() : fd(-1) { }
+    QDBusUnixFileDescriptorPrivate(const QDBusUnixFileDescriptorPrivate &other)
+        : QSharedData(other), fd(-1)
+    {  }
+    ~QDBusUnixFileDescriptorPrivate();
+
+    QAtomicInt fd;
+};
+
+template<> inline
+QExplicitlySharedDataPointer<QDBusUnixFileDescriptorPrivate>::~QExplicitlySharedDataPointer()
+{ if (d && !d->ref.deref()) delete d; }
+
+QDBusUnixFileDescriptor::QDBusUnixFileDescriptor()
+    : d(0)
+{
+}
+
+QDBusUnixFileDescriptor::QDBusUnixFileDescriptor(int fileDescriptor)
+    : d(0)
+{
+    if (fileDescriptor != -1)
+        setFileDescriptor(fileDescriptor);
+}
+
+QDBusUnixFileDescriptor::QDBusUnixFileDescriptor(const QDBusUnixFileDescriptor &other)
+    : d(other.d)
+{
+}
+
+QDBusUnixFileDescriptor &QDBusUnixFileDescriptor::operator=(const QDBusUnixFileDescriptor &other)
+{
+    if (this != &other)
+        d.operator=(other.d);
+    return *this;
+}
+
+QDBusUnixFileDescriptor::~QDBusUnixFileDescriptor()
+{
+}
+
+bool QDBusUnixFileDescriptor::isValid() const
+{
+    return d ? d->fd != -1 : false;
+}
+
+bool QDBusUnixFileDescriptor::isShared() const
+{
+    return d && d->ref == 1;
+}
+
+int QDBusUnixFileDescriptor::fileDescriptor() const
+{
+    return d ? d->fd.operator int() : -1;
+}
+
+// actual implementation
+#ifdef Q_OS_UNIX
+
+bool QDBusUnixFileDescriptor::isSupported()
+{
+    return true;
+}
+
+void QDBusUnixFileDescriptor::setFileDescriptor(int fileDescriptor)
+{
+    if (fileDescriptor != -1)
+        giveFileDescriptor(qt_safe_dup(fileDescriptor));
+}
+
+void QDBusUnixFileDescriptor::giveFileDescriptor(int fileDescriptor)
+{
+    // if we are the sole ref, d remains unchanged
+    // if detaching happens, d->fd will be -1
+    if (d)
+        d.detach();
+    else
+        d = new QDBusUnixFileDescriptorPrivate;
+
+    if (d->fd != -1)
+        qt_safe_close(d->fd);
+
+    if (fileDescriptor != -1)
+        d->fd = fileDescriptor;
+}
+
+int QDBusUnixFileDescriptor::takeFileDescriptor()
+{
+    if (!d)
+        return -1;
+
+    return d->fd.fetchAndStoreRelaxed(-1);
+}
+
+QDBusUnixFileDescriptorPrivate::~QDBusUnixFileDescriptorPrivate()
+{
+    if (fd != -1)
+        qt_safe_close(fd);
+}
+
+#else
+bool QDBusUnixFileDescriptor::isSupported()
+{
+    return false;
+}
+
+void QDBusUnixFileDescriptor::setFileDescriptor(int)
+{
+}
+
+void QDBusUnixFileDescriptor::giveFileDescriptor(int)
+{
+}
+
+int QDBusUnixFileDescriptor::takeFileDescriptor()
+{
+    return -1;
+}
+
+QDBusUnixFileDescriptorPrivate::~QDBusUnixFileDescriptorPrivate()
+{
+}
+
+#endif
diff --git a/src/dbus/qdbusunixfiledescriptor.h b/src/dbus/qdbusunixfiledescriptor.h
new file mode 100644
index 0000000..3ac3f9f
--- /dev/null
+++ b/src/dbus/qdbusunixfiledescriptor.h
@@ -0,0 +1,103 @@
+/****************************************************************************
+**
+** 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 FOO 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.
+**
+**
+**
+**
+**
+**
+**
+**
+** $QT_END_LICENSE$
+**
+****************************************************************************/
+
+
+#ifndef QDBUSUNIXFILEDESCRIPTOR_H
+#define QDBUSUNIXFILEDESCRIPTOR_H
+
+#include <QtCore/QSharedDataPointer>
+#include <QtDBus/qdbusmacros.h>
+
+#ifndef QT_NO_DBUS
+
+#ifdef Q_COMPILER_RVALUE_REFS
+# include <utility>
+#endif
+
+QT_BEGIN_HEADER
+
+QT_BEGIN_NAMESPACE
+
+QT_MODULE(DBus)
+
+class QDBusUnixFileDescriptorPrivate;
+template<> QExplicitlySharedDataPointer<QDBusUnixFileDescriptorPrivate>::~QExplicitlySharedDataPointer();
+
+class Q_DBUS_EXPORT QDBusUnixFileDescriptor
+{
+public:
+    QDBusUnixFileDescriptor();
+    explicit QDBusUnixFileDescriptor(int fileDescriptor);
+    QDBusUnixFileDescriptor(const QDBusUnixFileDescriptor &other);
+    QDBusUnixFileDescriptor &operator=(const QDBusUnixFileDescriptor &other);
+    ~QDBusUnixFileDescriptor();
+
+    bool isValid() const;
+    bool isShared() const;
+
+    int fileDescriptor() const;
+    void setFileDescriptor(int fileDescriptor);
+
+    void giveFileDescriptor(int fileDescriptor);
+    int takeFileDescriptor();
+
+    static bool isSupported();
+
+#if defined(Q_COMPILER_RVALUE_REFS)
+    QDBusUnixFileDescriptor(QDBusUnixFileDescriptor &&other) : d(static_cast<Data &&>(other.d))
+    { }
+    inline QDBusUnixFileDescriptor &operator=(QDBusUnixFileDescriptor &&other)
+    { d.swap(other.d); return *this; }
+#endif
+
+protected:
+    typedef QExplicitlySharedDataPointer<QDBusUnixFileDescriptorPrivate>  Data;
+    Data d;
+};
+
+QT_END_NAMESPACE
+
+Q_DECLARE_METATYPE(QDBusUnixFileDescriptor)
+
+QT_END_HEADER
+
+#endif // QT_NO_DBUS
+#endif // QDBUSUNIXFILEDESCRIPTOR_H