Long live QRandomGenerator

This class provides a reasonably-secure random number generator that
does not need seeding. That is quite unlike qrand(), which requires a
seed and is low-quality (definitely not secure).

This class is also like std::random_device, but better. It provides an
operator() like std::random_device, but unlike that, it also provides a
way to fill a buffer with random data, not just one 32-bit quantity.
It's also stateless.

Finally, it also implements std::seed_seq-like generate(). It obeys the
standard requirement of the range (32-bit) but not that of the algorithm
(if you wanted that, you'd use std::seed_seq itself). Instead,
generate() fills with pure random data.

Change-Id: Icd0e0d4b27cb4e5eb892fffd14b4e3ba9ea04da8
Reviewed-by: Lars Knoll <lars.knoll@qt.io>

1 files changed, 78 insertions, 0 deletions

diff --git a/src/corelib/global/qrandom_p.h b/src/corelib/global/qrandom_p.h
new file mode 100644
index 0000000000..6ac2904e1b
--- /dev/null
+++ b/src/corelib/global/qrandom_p.h
@@ -0,0 +1,78 @@
+/****************************************************************************
+**
+** Copyright (C) 2017 Intel Corporation.
+** Contact: https://www.qt.io/licensing/
+**
+** This file is part of the QtCore module of the Qt Toolkit.
+**
+** $QT_BEGIN_LICENSE:LGPL$
+** Commercial License Usage
+** Licensees holding valid commercial Qt licenses may use this file in
+** accordance with the commercial license agreement provided with the
+** Software or, alternatively, in accordance with the terms contained in
+** a written agreement between you and The Qt Company. For licensing terms
+** and conditions see https://www.qt.io/terms-conditions. For further
+** information use the contact form at https://www.qt.io/contact-us.
+**
+** GNU Lesser General Public License Usage
+** Alternatively, this file may be used under the terms of the GNU Lesser
+** General Public License version 3 as published by the Free Software
+** Foundation and appearing in the file LICENSE.LGPL3 included in the
+** packaging of this file. Please review the following information to
+** ensure the GNU Lesser General Public License version 3 requirements
+** will be met: https://www.gnu.org/licenses/lgpl-3.0.html.
+**
+** GNU General Public License Usage
+** Alternatively, this file may be used under the terms of the GNU
+** General Public License version 2.0 or (at your option) the GNU General
+** Public license version 3 or any later version approved by the KDE Free
+** Qt Foundation. The licenses are as published by the Free Software
+** Foundation and appearing in the file LICENSE.GPL2 and LICENSE.GPL3
+** included in the packaging of this file. Please review the following
+** information to ensure the GNU General Public License requirements will
+** be met: https://www.gnu.org/licenses/gpl-2.0.html and
+** https://www.gnu.org/licenses/gpl-3.0.html.
+**
+** $QT_END_LICENSE$
+**
+****************************************************************************/
+
+#ifndef QRANDOM_P_H
+#define QRANDOM_P_H
+
+//
+//  W A R N I N G
+//  -------------
+//
+// This file is not part of the Qt API.  It exists purely as an
+// implementation detail.  This header file may change from version to
+// version without notice, or even be removed.
+//
+// We mean it.
+//
+
+#include "qglobal_p.h"
+
+QT_BEGIN_NAMESPACE
+
+enum QRandomGeneratorControl {
+    SkipMemfill = 1,
+    SkipSystemRNG = 2,
+    SkipHWRNG = 4,
+    SetRandomData = 8,
+
+    // 28 bits
+    RandomDataMask = 0xfffffff0
+};
+
+#if defined(QT_BUILD_INTERNAL) && defined(QT_BUILD_CORE_LIB)
+Q_CORE_EXPORT QBasicAtomicInteger<uint> qt_randomdevice_control = Q_BASIC_ATOMIC_INITIALIZER(0U);
+#elif defined(QT_BUILD_INTERNAL)
+extern Q_CORE_EXPORT QBasicAtomicInteger<uint> qt_randomdevice_control;
+#else
+enum { qt_randomdevice_control = 0 };
+#endif
+
+QT_END_NAMESPACE
+
+#endif // QRANDOM_P_H