Unify QByteArray::MaxSize and MaxAllocSize

We have established the maximum size qAllocMore can deal with in
commit 880986be2357a1f80827d038d770dc2f80300201 and we should use
it.

The maximum size for byte arrays is reduced by one byte as with
the previous code we could make qAllocMore produce ((1 << 31) - extra)
by passing (1 << 30). That is not a problem for qAllocMore itself
(as long as extra > 0) but it's hard to verify that no related
code casts the total sum back to signed int, which would overflow
to -1.

To make the compiler inline access to the maximum size, a private
enum MaxByteArraySize is provided, which can be used in internal
code.

This fixes the merge of commits
880986be2357a1f80827d038d770dc2f80300201 and
c70658d301e274c3aaa1fb6cebe2a5e56db12779

Change-Id: Idb04856f7c2e53ef383063e7555d3083020ff2b7
Reviewed-by: Thiago Macieira <thiago.macieira@intel.com>

1 files changed, 61 insertions, 0 deletions

diff --git a/src/corelib/tools/qbytearray_p.h b/src/corelib/tools/qbytearray_p.h
new file mode 100644
index 0000000000..78c667aa90
--- /dev/null
+++ b/src/corelib/tools/qbytearray_p.h
@@ -0,0 +1,61 @@
+/****************************************************************************
+**
+** Copyright (C) 2015 The Qt Company Ltd.
+** Contact: http://www.qt.io/licensing/
+**
+** This file is part of the QtCore module of the Qt Toolkit.
+**
+** $QT_BEGIN_LICENSE:LGPL21$
+** 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 http://www.qt.io/terms-conditions. For further
+** information use the contact form at http://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 2.1 or version 3 as published by the Free
+** Software Foundation and appearing in the file LICENSE.LGPLv21 and
+** LICENSE.LGPLv3 included in the packaging of this file. Please review the
+** following information to ensure the GNU Lesser General Public License
+** requirements will be met: https://www.gnu.org/licenses/lgpl.html and
+** http://www.gnu.org/licenses/old-licenses/lgpl-2.1.html.
+**
+** As a special exception, The Qt Company gives you certain additional
+** rights. These rights are described in The Qt Company LGPL Exception
+** version 1.1, included in the file LGPL_EXCEPTION.txt in this package.
+**
+** $QT_END_LICENSE$
+**
+****************************************************************************/
+
+#ifndef QBYTEARRAY_P_H
+#define QBYTEARRAY_P_H
+
+//
+//  W A R N I N G
+//  -------------
+//
+// This file is not part of the Qt API.  It exists for the convenience
+// of other Qt classes.  This header file may change from version to
+// version without notice, or even be removed.
+//
+// We mean it.
+//
+
+#include <QtCore/qbytearray.h>
+#include <QtCore/qtypetraits.h>
+#include "qtools_p.h"
+
+QT_BEGIN_NAMESPACE
+
+enum {
+    // Define as enum to force inlining. Don't expose MaxAllocSize in a public header.
+    MaxByteArraySize = MaxAllocSize - sizeof(QtPrivate::remove_pointer<QByteArray::DataPtr>::type)
+};
+
+QT_END_NAMESPACE
+
+#endif // QBYTEARRAY_P_H