quuid_p.h - mozsearch

++ // Copyright (C) 2020 The Qt Company Ltd.

++ // Copyright (C) 2021 Intel Corporation.

++ // SPDX-License-Identifier: LicenseRef-Qt-Commercial OR LGPL-3.0-only OR GPL-2.0-only OR GPL-3.0-only

++ // Qt-Security score:significant reason:default

++

++ #ifndef QUUID_P_H

++ #define QUUID_P_H

++

++ //

++ //  W A R N I N G

++ //  -------------

++ //

++ // This file is not part of the Qt API.  It exists for the convenience

++ // of the QLibrary class.  This header file may change from

++ // version to version without notice, or even be removed.

++ //

++ // We mean it.

++ //

++

++ #include "quuid.h"

++

++ #include <QtCore/qrandom.h>

++

++ #include <chrono>

++

++ QT_BEGIN_NAMESPACE

++

++ #ifndef QT_BOOTSTRAPPED

++ static inline QUuid createUuidV7_internal(

++     std::chrono::time_point<std::chrono::system_clock, std::chrono::nanoseconds> tp)

++ {

++     QUuid result;

++

++     using namespace std::chrono;

++     const nanoseconds nsecSinceEpoch = tp.time_since_epoch();

++     const auto msecSinceEpoch = floor<milliseconds>(nsecSinceEpoch);

++     const quint64 frac = (nsecSinceEpoch - msecSinceEpoch).count();

++     // Lower 48 bits of the timestamp

++     const quint64 msecs = quint64(msecSinceEpoch.count()) & 0xffffffffffff;

++     result.data1 = uint(msecs >> 16);

++     result.data2 = ushort(msecs);

++     // rand_a: use a 12-bit sub-millisecond timestamp for additional monotonicity

++     // https://datatracker.ietf.org/doc/html/rfc9562#monotonicity_counters (Method 3)

++

++     // "frac" is a number between 0 and 999,999, so the lowest 20 bits

++     // should be roughly random. Use the high 12 of those for additional

++     // monotonicity.

++     result.data3 = frac >> 8;

++     result.data3 &= 0x0FFF;

++     result.data3 |= ushort(7) << 12;

++

++     // rand_b: 62 bits of random data (64 - 2 bits for the variant)

++     const quint64 random = QRandomGenerator::system()->generate64();

++     memcpy(result.data4, &random, sizeof(quint64));

++     result.data4[0] = (result.data4[0] & 0x3F) | 0x80; // UV_DCE

++     return result;

++ }

++ #endif

++

++ QT_END_NAMESPACE

++

++ #endif // QUUID_P_H

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