Core: add some commonly used QUniqueHandle types

QUniqueHandle allows us to write RAII types for non-trivial classes. We
can add some specialisations for 2 types of win32 handles, file
descriptors and FILE*

Pick-to: 6.8
Change-Id: I4d6af274bcc7f84ae009d0cb3a2f3aec1b6bcaf9
Reviewed-by: Thiago Macieira <thiago.macieira@intel.com>

src/corelib/CMakeLists.txt

@@ -316,6 +316,7 @@ qt_internal_add_module(Core
         tools/qtools_p.h
         tools/qtyperevision.cpp tools/qtyperevision.h
         tools/quniquehandle_p.h
+        tools/quniquehandle_types.cpp tools/quniquehandle_types_p.h
         tools/qvarlengtharray.h
         tools/qvector.h
         tools/qversionnumber.cpp tools/qversionnumber.h

src/corelib/tools/quniquehandle_types.cpp

@@ -0,0 +1,52 @@
+// Copyright (C) 2024 The Qt Company Ltd.
+// SPDX-License-Identifier: LicenseRef-Qt-Commercial OR LGPL-3.0-only OR GPL-2.0-only OR GPL-3.0-only
+
+#include <QtCore/private/quniquehandle_types_p.h>
+
+#include "qplatformdefs.h" // For QT_CLOSE
+
+#ifdef Q_OS_WIN
+#  include <QtCore/qt_windows.h>
+#endif
+
+#ifdef Q_OS_UNIX
+#  include <QtCore/private/qcore_unix_p.h> // for qt_safe_close
+#endif
+
+QT_BEGIN_NAMESPACE
+
+namespace QtUniqueHandleTraits {
+
+#ifdef Q_OS_WIN
+
+bool InvalidHandleTraits::close(Type handle)
+{
+    return ::CloseHandle(handle);
+}
+
+bool NullHandleTraits::close(Type handle)
+{
+    return ::CloseHandle(handle);
+}
+
+#endif
+
+bool FileDescriptorHandleTraits::close(Type handle)
+{
+    return QT_CLOSE(handle) == 0;
+}
+
+bool FILEHandleTraits::close(Type handle)
+{
+    return ::fclose(handle);
+}
+
+} // namespace QtUniqueHandleTraits
+
+#ifdef Q_OS_UNIX
+
+using QUniqueFileDescriptorHandle = QUniqueHandle<QtUniqueHandleTraits::FileDescriptorHandleTraits>;
+
+#endif
+
+QT_END_NAMESPACE

src/corelib/tools/quniquehandle_types_p.h

@@ -0,0 +1,81 @@
+// Copyright (C) 2024 The Qt Company Ltd.
+// SPDX-License-Identifier: LicenseRef-Qt-Commercial OR LGPL-3.0-only OR GPL-2.0-only OR GPL-3.0-only
+
+#ifndef QUNIQUEHANDLE_TYPES_P_H
+#define QUNIQUEHANDLE_TYPES_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 <QtCore/qglobal.h>
+#include <QtCore/private/quniquehandle_p.h>
+
+#include <cstdio>
+
+QT_BEGIN_NAMESPACE
+
+namespace QtUniqueHandleTraits {
+
+#ifdef Q_OS_WIN
+
+struct InvalidHandleTraits
+{
+    using Type = Qt::HANDLE;
+    static Type invalidValue() noexcept
+    {
+        return Qt::HANDLE(-1); // AKA INVALID_HANDLE_VALUE
+    }
+    Q_CORE_EXPORT static bool close(Type handle);
+};
+
+struct NullHandleTraits
+{
+    using Type = Qt::HANDLE;
+    static Type invalidValue() noexcept { return nullptr; }
+    Q_CORE_EXPORT static bool close(Type handle);
+};
+
+#endif
+
+struct FileDescriptorHandleTraits
+{
+    using Type = int;
+    static constexpr Type invalidValue() noexcept { return -1; }
+    Q_CORE_EXPORT static bool close(Type handle);
+};
+
+struct FILEHandleTraits
+{
+    using Type = FILE *;
+    static constexpr Type invalidValue() noexcept { return nullptr; }
+    Q_CORE_EXPORT static bool close(Type handle);
+};
+
+} // namespace QtUniqueHandleTraits
+
+#ifdef Q_OS_WIN
+
+using QUniqueWin32Handle = QUniqueHandle<QtUniqueHandleTraits::InvalidHandleTraits>;
+using QUniqueWin32NullHandle = QUniqueHandle<QtUniqueHandleTraits::NullHandleTraits>;
+
+#endif
+
+#ifdef Q_OS_UNIX
+
+using QUniqueFileDescriptorHandle = QUniqueHandle<QtUniqueHandleTraits::FileDescriptorHandleTraits>;
+
+#endif
+
+using QUniqueFILEHandle = QUniqueHandle<QtUniqueHandleTraits::FILEHandleTraits>;
+
+QT_END_NAMESPACE
+
+#endif