| 1 | // Copyright (C) 2020 The Qt Company Ltd. |
|---|---|
| 2 | // Copyright (C) 2021 Intel Corporation. |
| 3 | // SPDX-License-Identifier: LicenseRef-Qt-Commercial OR LGPL-3.0-only OR GPL-2.0-only OR GPL-3.0-only |
| 4 | |
| 5 | #ifndef QUUID_P_H |
| 6 | #define QUUID_P_H |
| 7 | |
| 8 | // |
| 9 | // W A R N I N G |
| 10 | // ------------- |
| 11 | // |
| 12 | // This file is not part of the Qt API. It exists for the convenience |
| 13 | // of the QLibrary class. This header file may change from |
| 14 | // version to version without notice, or even be removed. |
| 15 | // |
| 16 | // We mean it. |
| 17 | // |
| 18 | |
| 19 | #include "quuid.h" |
| 20 | |
| 21 | #include <QtCore/qrandom.h> |
| 22 | |
| 23 | #include <chrono> |
| 24 | |
| 25 | QT_BEGIN_NAMESPACE |
| 26 | |
| 27 | #ifndef QT_BOOTSTRAPPED |
| 28 | static inline QUuid createUuidV7_internal( |
| 29 | std::chrono::time_point<std::chrono::system_clock, std::chrono::nanoseconds> tp) |
| 30 | { |
| 31 | QUuid result; |
| 32 | |
| 33 | using namespace std::chrono; |
| 34 | const nanoseconds nsecSinceEpoch = tp.time_since_epoch(); |
| 35 | const auto msecSinceEpoch = floor<milliseconds>(d: nsecSinceEpoch); |
| 36 | const quint64 frac = (nsecSinceEpoch - msecSinceEpoch).count(); |
| 37 | // Lower 48 bits of the timestamp |
| 38 | const quint64 msecs = quint64(msecSinceEpoch.count()) & 0xffffffffffff; |
| 39 | result.data1 = uint(msecs >> 16); |
| 40 | result.data2 = ushort(msecs); |
| 41 | // rand_a: use a 12-bit sub-millisecond timestamp for additional monotonicity |
| 42 | // https://datatracker.ietf.org/doc/html/rfc9562#monotonicity_counters (Method 3) |
| 43 | |
| 44 | // "frac" is a number between 0 and 999,999, so the lowest 20 bits |
| 45 | // should be roughly random. Use the high 12 of those for additional |
| 46 | // monotonicity. |
| 47 | result.data3 = frac >> 8; |
| 48 | result.data3 &= 0x0FFF; |
| 49 | result.data3 |= ushort(7) << 12; |
| 50 | |
| 51 | // rand_b: 62 bits of random data (64 - 2 bits for the variant) |
| 52 | const quint64 random = QRandomGenerator::system()->generate64(); |
| 53 | memcpy(dest: result.data4, src: &random, n: sizeof(quint64)); |
| 54 | result.data4[0] = (result.data4[0] & 0x3F) | 0x80; // UV_DCE |
| 55 | return result; |
| 56 | } |
| 57 | #endif |
| 58 | |
| 59 | QT_END_NAMESPACE |
| 60 | |
| 61 | #endif // QUUID_P_H |
| 62 |